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EARL WARREN, Governor 







JUNE 1950 









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To His Excellency 

The Honorable Earl Warren 

Governor of the State of California 


I have the honor to transmit herewith Bulletin 150, Geology of 
Southwestern Santa Barbara County, California, prepared under the 
direction of Olaf P. Jenkins, Chief of the Division of Mines, Department 
of Natural Kesources. The report covers an area topographically mapped 
by the Federal Government in five 15-minute quadrangles comprising an 
area of 700 square miles, namely : Point Arguello, Lompoc, Point Con- 
ception, Los Olivos, and Gaviota quadrangles. In this report the geology 
of the area is described in great detail and graphically shown on colored 
lithograph maps which are accompanied by stratigraphic, structural, 
and physiographic diagrams. The economic minerals of the area are also 
described and mapped. These include oil and gas, asphalt, diatomite, 
limestone, bentonite, flagstone, road gravel, manganese ore, and ground 
water. The report describes three important oil fields — Capitan, Lompoc, 
and Zaca, as well as the world 's largest diatomite quarries. 

The author of this comprehensive report, T. W. Dibblee Jr., spent 
some 20 years studying the region, partly as a private venture in research, 
and partly in the employ of two major oil companies. Acknowledgment is 
made by Mr. Dibblee to these companies, namely, the Union Oil Company 
and the Richfield Oil Corporation, for their generosity in permitting the 
material to be made available to the public through the auspices of the 
State Division of Mines. 

Respectfully submitted, 

Department of Natural Resources 
December 1, 1949 










The early explorers 9 

The missions : 10 

The ranches 10 

Lompuc Valley 13 

Santa Tnez Yalley 13 




Physiographic features 17 

Drainage 19 

Erosion cycles 19 


Franciscan formation 21 

Honda formation 22 

Espada formation 22 

Jalama formation 23 

The Eocene-Oligocene series 24 

Eocene at Wons Canyon 25 

Sierra Blanca limestone 25 

Anita shale 26 

Matilija sandstone 26 

Cozy bell shale 27 

Sacate ("Coldwater"' j formation 28 

Gaviota formation 29 

Alegria formation 30 

Sespe formation 31 

Vaqueros formation 31 

Rincon elaystone 33 

Lospe formation 33 

Tranquillon volcanies 33 

^lonterey shale : 34 

Sisquoc formation 43 

Foxen elaystone 44 

Careaga sand 45 

Paso Robles formation 47 

Orcutt sand ^_^ 50 

Terrace deposits 50 

Alluvium 50 


Santa Ynez Mountains 53 

Southern structural block 53 

Northern structural block 53 

Santa Ynez fault system 54 

Other faults in Santa Ynez Mountains 56 

Lompoc Valley and Burton Mesa 58 

Santa Rita Valley and lower Santa Ynez Valley 58 

Purisima Hills 59 

Los Alamos Valley and upper Santa Ynez Valley 59 

San Rafael foothills 60 

San Rafael Mountains 60 



Oil and gas 67 

Santa Barbara-Ventura Basin 67 

Santa Maria Basin ^ 1 68 

Asphalt 75 


CONTENTS— Continued 


Diatomite 75 

Types of diatomite 75 

Deposits soutli of Lompoc Valley 76 

Deposits of Purisima Hills and Santa Tnez Valley 77 

Uses of diatomite 77 

Diatomite quarries 77 

Limestone 79 

Bentonite 80 

Flagstone 80 

Road gravel . 80 

Manganese oi-e 81 

Water 82 




Plate 1. Geologic map of Point Arguello, Lompoc, and Point Conception 

quadrangles In pocket 

2. Geologic map of Los Olivos and Gaviota quadrangles In pocket 

3. Economic map of Point Arguello, Lompoc, and Point Conception 

quadrangles In pocket 

4. Economic map of Los Olivos and Gaviota quadrangles In pocket 

5. Geologic structure sections across southwestern Santa Barbara 

County In pocket 

6. Areal map showing generalized geology of southwestern Santa 

Barbara County In pocket 

7. A, Tectonic map of southwestern Santa Barbara County. B, 

Physiographic map of southwestern Santa Barbara County In pocket 

8. Structural map of the Lompoc oil field In pocket 

9. Aerial photographs, southwestern Santa Barbara County In pocket 

10. A, View west along Santa Ynez Range from head of Jalama 

Canyon. B, View east along western Santa Ynez Mountains, 

from head of El Bulito Canyon 32-33 

11. A, View west across Caiiada del Gato on south flank of Santa 

Ynez Mountains. B, View northeast from Gaviota showing 
outcrops of Alegria sandstone 32-33 

12. A, Angular unconformity between Eocene fossiliferous sandstone 

(Matilija) and Cretaceous shale (Jalama?). B, View west 

across Nojoqui Canyon 2.5 miles south of Buellton 32-33 

13. A, Vaqueros conglomerate in Ramajal Canyon. B, Steeply dip- 

ping limestone bed in Member B, lower Monterey shale, east 

of Alegria Canyon 32-33 

14. Platy porcelaneous siliceous shales of Member F, upper Monte- 

rey, near mouth of Alegria Canyon 40-41 

15. A, Thin-bedded foraminiferal shale of Member D, lower Monterey 

shale, in Alegria Canyon. B, Cherty siliceous shales of Member 

E, upper Monterey shale, near mouth of Jalama Canyon 40-41 

16. A, View west along coast from mouth of Cuarta Canyon. B, 

Typical exposure of Paso Robles terrestrial conglomerate, 7 

miles east of Santa Ynez 40-41 

17. Tar-soaked conglomerate and sandstone near top of Monterey 

shale, east of Alegria Canyon half a mile from beach 40-41 

Figure 1. Index map showing location of Point Arguello, Lompoc, Point 
Conception, Los Olivos, and Gaviota quadrangles, southwest- 
ern Santa Barbara County 8 

2. Stratigraphic column, western Santa Ynez Mountains 38 

3. Stratigraphic column, southern Santa Maria Basin 39 

4. Chart showing age of formations in southwestern Santa Barbara 

County 48 

5. Tectonics of step-faulting in Alisal-Nojoqui area, Santa Barbara 

County 52 

6. Structural map of Capitan oil field, Santa Barbara County 66 




(Point Arguello, Lompoc, Point Conception, Los Olivos, 
and Gaviota Quadrangles) 

By T. W. Dibblee Jel* 


The PoiBt Arguello. Lompoc. Ix.s Olivos. Point Conception, and Gaviota quad- 
rangles comprise the southwestern quarter of Santa Barbara County, and cover the 
western Santa Tnez Mountains, southern portion of Santa Maria Basm, and a smaU 
portion of the San Rafael Mountains. 4.u„ u;„i,or 

The Santa Tnez :Mountains are composed of two topographic parts , the higher 
Santa Tnez Range on the southeast, and the lower Santa Tnez Mountains on the 
northwest. The Santa Maria Basin is made up on the south of the lowlands of Burton 
Mesa. Lompoc Valley and Santa Tnez Valley, which are traversed by the westward- 
flowin- Santa Tnez River : and on the north of the Purisima HiUs and San Rafael 
foothais, in part separated by Los Alamos Valley. The region is in the mature stage of 
the erosion cycle. Remnants of an earlier cycle, which reached late maturity, are 

locallv preserved. . ^i. c <- -^^^^ 

The area mapped is composed of two stratigraphic provinces, the J>anta Inez 
Alountains on the south and the Santa Maria Basin on the north. The Franciscan 
formation (Upper Jurassic ? ) , a series of sedimentary and volcanic rocks with numer- 
ous serpentinized intrusions, is the basement formation of both provinces. The Espada 
formation (Upper Jurassic and Lower Cretaceous) is weU developed in the l-anta 
Tnez Mountains and mav locally underlie the Santa :Slaria Basin. In the Santa Inez 
Mountains this formation is overlain by a very thick series of predominantly marine 
Upper Cretaceous. Eocene. Oligocene. and lower Miocene clastic sediments. TN ith the 
exception of the lower Miocene, these are absent in the Santa Maria Basin. Marine 
siliceous sediments of the Monterey and Sisquoc formations (middle Miocene through 
lower Pliocene i are common to both areas but become extremely thick in the banta 
Maria Basin. The former locaUy contains some volcanic rocks at the base m the J^anta 
Tnez Mountains. The Sisquoc in the Santa Maria Basin is overlain by the marine 
Foxen shale and Careaga sand (upper Pliocene) and the terrestrial Paso Robles and 
Orcutt formations <Plio-Pleistocene). 

The Santa Tnez Mountains and Santa Maria Basin are separate structural 
provinces The Santa Tnez Mouutains are made up of two structural units: the 
southern portion is a south-dipping homocline in a very thick stratigraphic section 
uplifted on the north along the Santa Tnez fault zone, and the northern portion is an 
anticlinorum composed of numerous folds developed in a thinning stratigraphic section 
with manv unconformities. In the Santa Maria Basin the Burton Mesa-LompocJ^ alley- 
lower Santa Tnez Vallev portion is a structuraUy rigid wedge-shaped area of Fran- 
ciscan rocks covered bv a thin Tertiary-Quaternary section only slightly deformed Ihe 
structure of Los Alamos and upper Santa Tnez VaUeys is a synclinal trough developed 
in an extremelv thick Tertiary-Quaternary section, which is flanked by the anticlinal 
Purisima HiUs and San Rafael foothills. The San Rafael Mountains withm Los Olivos 
quadrangle are a mass of Franciscan rocks thrust southwestward toward the San 

Rafael foothills. . , . , o. ^ t. u „ 

Formations of the Santa Tnez Mountains were deposited in the Santa Barbara 
embavment which underwent sedimentation from Cretaceous to Pliocene time. The 
Santa Maria Basin developed during Miocene time and received sediments throughout 
the Pliocene and Pleistocene. Tectonic history indicates that the structures withm the 
area are the result of a recurrent stress system active as far back as Oligocene. and 
possibly even early Eocene or Cretaceous time, but most intense in Pliocene and 
Pleistocene time. 

^^ologist, Richfield Oil Corporation. Manuscript submitted for publication Jan- 
uary 1949. 




[Bull. 150 

Figure 1. Index map showing location of Point Arguello, Lompoc, Point Conception, 
Los Olivos, and Gaviota quadrangles, southwestern Santa Barbara County. 

Petroleum is the most important economic resource of the mapped area, which 
contains three highly productive oil fields. Capitan field on the south coast produces 
light oil and some gas. Lompoc and Zaca fields in the Santa Maria Basin produce 
medium and heavy oil. Deposits of tar sand occur in the Purisima Hills but none have 
been worked commercially. 

The northwestern Santa Ynez Mountains contain large deposits of high-gi-ade 
diatomite. The Johns-Manville quarries south of Lompoc are the largest diatomite 
quarries in the world. Limestone deposits occur in the Miocene of the northwestern 
Santa Ynez Mountains, but have been quarried only for road gravel. Sand, gravel, and 
cherty shale are also quarried for road material. 



The soutliwesteru portion of Santa Barbara County is an area of 
Franciscan basement overlain by a sequence of predominantly marine 
sedimentary formations and one local volcanic formation. The area is 
made up of parts of two geologic provinces roughly separated by the 
westward-flowing Santa Ynez River. 

The Santa Ynez Mountains lie south of the river and trend eastward 
parallel to the Santa Barbara Channel on the south. The Franciscan in 
this range is overlain by a nearly continuous .series of predominantly 
marine sedimentary formations ranging in age from uppermost Jurassic 
to Pliocene. These formations are very thick and conformable on the south 
flank, but thin rapidly to the north, where there are several uncon- 
formities. Structurally the high southern portion of this range is a south- 
dipping homocline uplifted on the north along the Santa Ynez fault 
sj^stem, while the lower northern portion is largelj- an area of folding. 

The lowland area north of the river takes in the southern portion of 
the Santa ]\Iaria Basin, which within the area mapped comprises the 
Lompoe Valley, Santa Ynez Valley, Burton Mesa, Purisima Hills, and 
parts of Los Alamos Valley and San Rafael foothills. The stratigraphic 
section of this basin consists of marine ]Mioceue and Pliocene and terres- 
trial Pleistocene which becomes very thick along the Los Alamos synclinal 
trough. The Burton Mesa, Purisima Hills, and San Rafael foothills are 
anticlinal areas ; the intervening valleys are sjTiclinal. 

The small portion of the San Rafael ^Mountains mapped is a block 
of Franciscan rocks thrust southwest toward the Santa ]\laria Basin. 


For permission to publish the geologic maps and this report, the 
writer is deeply indebted to L^nion Oil Company of Califoimia, and to 
Richfield Oil Corporation. The writer is also indebted- to R. K. Cross, 
for the portion of the area mapped by him ; to M. L. Xatland and W. T. 
Rothwell, for assistance rendered in microfaunal determinations; to 
A. W. Hughes, and to T. W. Dibblee and C. E. Russel, manager and 
foreman, respectively, of Rancho San Julian, for their cooperation and 
for use of the ranch house as headquarters while carrying on the work ; 
and to the owners and superintendents of the various ranches through- 
out the area. 


The Early Explorers 

The Santa Barbara coa.stal area was first explored by Cabrillo and 
Ferrelo in two small ships, in October 1542. After exploring the south 
coast and the islands thej- encountered such stormy weather where the 
coast "veered northward" (Pt. Conception) that they were forced to 
remain several days in the channel before resuming their journey. They 
spent several days at or near Refugio (Refuge) Beach, where they were 
met by friendly Indians who offered fresh sardines and other food. 

The earliest land expedition was led by Gaspar de Portola. accom- 
panied by Padre Junipero Serra and his ardent Franciscan monks, in 
1767, who took possession of Alta California in the name of the King 
of Spain. In traversing what is now Santa Barbara County the party 


traveled up the coast. Along the channel coast the native Indians Avere 
so friendly as to oft'er an abundance of seeds, acorns and fresli fish, in 
return for beads and other trinkets, and even begged the travelers to 
remain with them and share their huts. 

This same route was followed by the expedition of Juan Bautista 
de Anza in 1774 and 1775. 

Spanish explorers and mission padres were very much impressed 
by the beautiful region that is now Santa Barbara County, which 
bears striking resemblance to their mother country. They found a brush- 
covered mountain ridge (Santa Ynez Range) sloping southward to grassy 
foothills bordering the sea, and northward to rolling foothills and fertile 
valleys covered with luxuriant grasses and scattered groves of oak. The 
climate was ideal the year round. The area offered great possibilities as 
grazing land for cattle and sheep. As the Spanish ' ' conquistadores " 
entered this land during the 18th century the primitive life of the native 
Indians gave way to the gay and colorful ''hacienda" era that centered 
in the great ranches and Franciscan missions. The Spanish crown 
rewarded the soldier-explorers with large grants of land, known as 
"ranchos, " and the padres received large tracts on which to establish 
their missions. 

The Missions 

Mission Santa Barbara, founded in 1786, was the first of the three 
missions established by the Franciscan padres (fathers) in what is 
now Santa Barbara County to convert the native Indians to Christians 
and into useful subjects. The other two missions were established in the 
Santa Ynez River valley. 

In the lower portion of the valley Mission La Purisima Concepcion 
was founded December 8, 1787, by Padre Lasuen, presidente of the Fran- 
ciscan missionaries and successor to Padre Junipero Serra. This was the 
eleventh of the 21 missions established in California; it was erected 
near the present site of the Veterans Memorial Building at Lompoc. The 
mission served the growing community of Indian neophytes until the 
earthquake of 1812 which almost completely destroyed it. It then became 
known as La Mision Vieja de la Purisima. In 1816 the mission was 
rebuilt at a new site at the mouth of Purisima Canyon, and was served 
by Franciscan friars until confiscated and sold by Mexican politicians 
in 1845. It was then abandoned and became a ruin, but was restored 
after 1933 by the federal government and made into a state park and 

In the upper portion of Santa Ynez River valley. Mission Santa 
Ines was founded at its present site at Solvang on September 17, 1804, 
by Padre Estavan Tapis, a.s the nineteenth mission established. The 
church and buildings were completed in 1812. The earthquake of that 
year damaged it, and the present church was completed in 1817. The 
mission was served by the Franciscan friars and was the site of the first 
seminary (priesthood) college in California, established in 1844. The 
mission was confiscated after the Mexican revolution, but is now a parish 
church in charge of the Capuchin Franciscans. 

The Ranches 

The historic background of southwestern Santa Barbara County 
centers in the great ranchos into which it was divided. These large tracts 
of land granted to the Spanish soldier-explorers in commendation of 

1950] HISTORY 11 

their services, are shown on the old topoc^raphic maps of Lompoc and 
Guadalupe quadrangles (scale 1 inch ^ 2 miles), issued by the U. S. 
Geological Survey in 1905. 

At each rancho the grantee built at or near a large spring an 
hacienda, a long, low house of adobe walls 2 or 3 feet thick, with a long 
front porch. Most of the houses were shaded by trees or grape arbors. 
Helping hands occupied smaller outbuildings. The ranchos were stocked 
with herds of Spanish cattle, which roamed at large, there being no 
fences. In the spring of each year rodeos (roundups) were held, during 
which the cattle were herded together, calves branded and steers sold. 
In addition, large numbers of sheep were raised on some ranchos. 
Although periodic droughts caused the loss of much livestock, the ran- 
cheros prospered from the sale of beef, hides, tallow, mutton, and wool 
while California was under the Spanish and Mexican flags, although 
much of the business was with Yankee traders from Boston and New 
York. Aside from the working of cattle and sheep there was little to do, 
so that the life of the Californians took on a gay fiesta spirit. 

When American explorers and troops invaded California during the 
Gold Rush era of the late forties, the rancheros offered no resistance, as 
they prospered from business with Yankee traders, and resented being 
taxed to the limit by greedy Mexican politicians. Being good Catholics, 
the rancheros likewise resisted confiscation of the missions. In 1846 
General John C. Fremont and his Yankee troops came south by way of 
Foxen Canyon and over San Marcos Pass, and took Santa Barbara 
without resistance. 

After California was annexed to the United States in 1850, the 
"gringos" (Yankees) settled in Santa Barbara County in ever increasing 
numbers, intermarried with the Spanish-Californians, and, since they 
were more ambitious and energetic, gradually acquired lands of the 
ranchos from the descendants of the grantees. As the ranchos became 
divided and subdivided into smaller and smaller tracts, fences were 
erected, and the valleys were cultivated. The semi-wild, long-horned 
Spanish cattle were gradually replaced by the large chunky ' ' white-face ' ' 
Herefords as the main source of beef, and by docile Holstein and Guern- 
sey cows as the source of dairy products. 

One of the most colorful of the Spanish ranchos is Rancho San Julian, 
whose history is in general typical of that of the other ranchos in the area. 
In 1817 the Company of the Presidio of Santa Barbara established 
Rancho San Julian as a source of meat supply for the soldiers of the 
King of Spain, and it was then kno-^vn as Rancho Nacional. At that time 
the first section of the present adobe house was built and served as head- 
quarters. In commendation for his many military services several ranchos 
were granted by the Spanish Crown to Capitan Jose Antonio de la Guerra 
y Noriega, who was born in Novales, Spain, in 1779, from a long line 
of distinguished ancestors. He came to California in 1800 and was sta- 
tioned at Santa Barbara in 1806 where he served for 24 years as com- 
mandante of the Presidio and was commissioned * ' Habilitado General ' ' 
(Resident General) of both Californias. In 1837 he became grantee of 
Rancho San Julian, comprising 11 leagues or 48,000 acres. In addition 
he was granted Rancho Los Alamos in Los Alamos Valley area, and 
Ranchos Simi, Tapo, and El Conejo in what is now Ventura County. 


Upon the death of Don Jose Antonio de la Gnerra y Noriega, Ranclio 
San Julian was inherited by his sons, one of whom was Pablo de la Guerra, 
and it later passed into the ownership of Don Gaspar Orena, their brother- 
in-law married to Maria Antonia de la Guerra. 

In 1867 Thos. Bloodgood Dibblee and his brother, Albert Dibblee, 
came to California from New York and purchased Rancho San Julian 
from Gaspar Oreiia and his wife, and a year later T. B. Dibblee married 
Francisca de la Guerra, daughter of Pablo de la Guerra. T. B. Dibblee 
stocked the rancho with one of the finest herds of registered shorthorn 
beef cattle known which for many years produced top grade foundation 

Soon after the Dibblee brothers acquired Rancho San Julian they 
formed a partnership with W. W. Hollister and purchased the adjoining 
Ranchos Espada, Lompoc, Mission Vieja de la Purisima, Caiiada de 
Salsipuedes, Las Cruces, and Nuestra Senora del Refugio. These vast, 
unfenced rangelands, totaling some 150,000 acres, were managed by 
T. B. Dibblee, and the San Julian ranch house (Casa de San Julian) 
was headquarters. The lands were stocked with both cattle and sheep. 

For the springtime rodeos, the vaqueros rode out many miles 
from Casa de San Julian to gather the cattle of each local area into 
corrals conveniently located. They were joined and assisted by vaqueros 
from neighboring ranchos in order to identify their respective cattle. 
After the cattle were gathered in, the calves were branded, and steers 
in good condition and any other cattle to be sold were separated out and 
driven to headquarters for sale. At nightfall the vaqueros often camped 
and ate barbecued steak under the oak trees. The rodeos lasted several 
weeks, often several days being required to work each local area. After 
the cattle brought in to headquarters were sold, they were driven to 
Gaviota Beach and loaded on board ship at a loading pier, built by 
T. B. Dibblee, and shipped to San Francisco, the main market. After the 
Pacific Railroad was built from that city south to Guadalupe, in Santa 
Maria Valley, in the nineties, the cattle were sometimes driven 30 miles 
. to that station (it took 4 days) and shipped north by rail. 

The lands of Dibblee and Hollister were at one time stocked with 
more than 50,000 head of sheep besides the cattle. This large herd con- 
sisted of many flocks each herded by a lonely shepherd, usually a 
Spanish-Basque, and his faithful dogs. He spent his lifetime in the hills 
with his flock, and was supplied each two weeks with provisions from 
headquarters. Several times a year he brought his flock in to headquarters 
to be sheared, dipped, and doctored, and to wean the lambs, and have 
the yearling wethers separated to be shipped north to market. Sometimes 
these were driven all the way to San Francisco, fed on the way, and sold. 

In the seventies the Dibblee-Hollister partnership was dissolved and 
the lands and livestock divided. Ranchos Espada, Lompoc, and Mission 
Vieja de la Purisima were sold. Ranchos Canada de Salsipuedes, Las 
Cruces, and Nuestra Seiiora del Refugio went to W. W. Hollister and 
were inherited by his son, James J. Hollister, present owner. The western 
portion of Rancho San Julian went to A. Dibblee and was sold years later. 
The eastern portion of Rancho San Julian was retained by T. B. Dibblee 
and his wife, Francisca de la Guerra, and upon their death was inherited 
by their seven children, one of whom is T. Wilson Dibblee who succeeds 
his father as manager. 

1950] HISTORY 


Rancho San Julian enjoys the distinction of being one of the few 
remaining California ranches owned by the descendants of its grantee. 
Still used as headquarters is the original adobe ' ' hacienda" with two-foot- 
thick walls, of which the west wing was built by the Spanish soldiers in 
1817. the central portion by Captain Jose Antonio de la Guerra in 1837, 
and the east wing by T. B. Dibblee about 1875. 

Lompoc Valley 

Rancho Lompoc. which included the wild, verdant valley now called 
Lompoc, was purchased by a determined group of California Yankees 
in 1874 who foresaw its tremendous agricultural possibilities. They set 
aside a corner of the rancho as a townsite and in 1875 founded the town 
of Lompoc. They advertised the valley 's potential greatness throughout 
America and soon farmers, dairymen, tradesmen, and professional men 
from every section arrived. They built up the town of Lompoc to a 
thriving little city of 6,500. 

Lompoc Valley is one of the most intensively and successfully 
farmed areas in the nation. Almost all of its rich alluvial soil is under 
irrigation and more than 50 varieties of vegetables and herbs are pro- 
duced on a year-round basis, which yield an annual income to Lompoc 
running into millions of dollars. 

Lompoc Valley is most famous for its acres of flowers. More than 500 
varieties of flowers are groAvn commercially for seed on over 2,500 acres 
of the valley floor, which in spring and summer make a floral display as 
colorful as can be imagined. Ideal climatic and soil conditions enable 
I Lompoc Valley to produce a wide variety of flower seed with a high 

« germination rate. 

Rancho Jesus ]\Iaria, which covers the sandy, windswept Burton 
Mesa, was acquired by the U. S. Army during the last war and built 
into one of California's largest military installations. The reservation 
covers 96,000 acres and was activated during the war. The Army plans 
to use it as a training ground for the peacetime military force. 

Santa Ynez Valley 

Upper Santa Ynez Valley has always been a grazing area as it is 
too arid and rolling for year-round farming. In late years much of it has 
been dry-farmed for grain and barley. A famous artesian spring issues 
from the southern portion, of which the water was used by native Indians 
who inhabited the vicinity until recent j^ears. The water was also used 
by the Franciscan friars to irrigate fields near j\Iission Santa Ines. 
Adjacent to this big spring is the pueblo of Santa Ynez, the oldest in 
Santa Ynez Valley, from which the valley derives its name. The pueblo 
consisted of a large wooden hotel, garage, and store, and served as a 
stopover for the stages going to and from Santa Barbara over San Marcos 
Pass. The old hotel burned down about 1935 and the pueblo never grew. 

The village of Los Olivos is built around f amous '* Mattel 's TaA^ern", 
which used to serve as a stopover for stage-coaches traveling between 
Santa Barbara and San Francisco. The lower portion of Santa Ynez 
Valley has been developed into a small but intensively farmed area, 
largely by immigrants from Denmark who settled there. About 1910 a 
group of Danes established near the Santa Ines mission a townsite which 
they named "Solvang" (Sunny Valley) . It is now a thriving community 


inhabited by several hundred Danes. Three miles down, the highway 
village of Buellton was centered around Andersen's Inn, home of 
"split pea soup." 


Location and Method of Work. The area mapped comprises the 
southwestern portion of Santa Barbara County, which lies about midway 
between Santa Barbara and Santa Maria. The area totals about 700 
square miles. 

The base maps used for plotting the areal geology are five 15-minute 
topographic quadrangles, scale 1 :62500, namely Point Arguello, Lompoc, 
Los Olivos, Point Conception, and Gaviota. These were issued in 1941 
by the U. S. Army Corps of Engineers. 

Areal geology was mapped in 1929 and 1930, then from 1936 to 
1939, in detail, on aerial photographs (approximate scales, 1 :20000 and 
1:24000). This geology was later transferred to the 15-minute topo- 
graphic quadrangles. Minor details have necessarily been omitted because 
of the much smaller scale of the quadrangles. The areal mapping was done 
by the writer throughout the area with the exception of that portion of 
the San Rafael foothills lying west of Santa Agueda-Lisque Canyons in 
northern Los Olivos quadrangle, which was mapped by R. K. Cross, but 
checked in the field by the writer. The geology of the Purisima Hills was 
taken from U. S. Geological Survey Oil & Gas Investigations Preliminary 
Map 14, with slight modifications by the writer. 

Accessibility and Transportation. With the exception of the higher 
part of the Santa Ynez Range, all points within the area lie mthin 2 miles 
of roads. The main coastal highway, U. S. 101, runs from Santa Barbara, 
18 miles east of Capitan, to Santa Maria, 18 miles northwest of Los 
Alamos. Towns within the area are all connected by good paved roads. 
Throughout the area are many secondary roads, both county and private. 
The Southern Pacific railroad follows the coast throughout the area. 

Population and Industry. Four towns lie along the course of the 
Santa Ynez River. Lompoc (population 6500) is the largest and most 
westerly. Camp Cooke is located 10 miles northwest, and Mission La 
Purisima Concepcion 3 miles northeast of Lompoc. Farther east along 
the river are Buellton (population 300), Solvang (400), site of Mission 
Santa Ines, and Santa Ynez (250). Other small towns are Los Olivos 
(250) and Los Alamos (300). 

The fertile lands of Los Alamos, Lompoc, and lower Santa Ynez 
Valleys are extensively cultivated for alfalfa and truck-gardening. They 
are irrigated from numerous wells. Upper Santa Ynez Valle}^ is largely 
dry-farmed. The luxuriant grasslands of the rolling hills throughout 
the area are devoted to pasturing of beef and dairy cattle. 

Land Divisions. With the exception of the United States National 
Forest land in the San Rafael and higher Santa Ynez Mountains, which 
is sectionized, practically all of western Santa Barbara County is covered 
by original Spanish land grants. Only very small areas not covered by 
the grants are sectionized. These land grants and sections are shown only 
on the Guadalupe and old Lompoc quadrangles, scale 1 :125,000, issued by 
the U. S. Geological Survey in 1943. 


CUmafe. The climate of southwestern Santa Barbara County is 
equitable and mild throughout the year, and semi-arid. Summers are kept 
cool by low marine fog at night, and by the prevailing northwest sea 
breeze during the day. Winters are mild, but night temperatures often 
fall below freezing in inland valleys. 

Precipitation is in the form of rainfall and may occur any time from 
October to May. but in most years heavy rains come only during the 
winter months. Annual rainfall averages about 15 inches throughout the 
area except in the Santa Ynez and San Rafael Mountains, where it 
averages about 25 inches. 

Exposures and Tegetation. Exposures throughout the area mapped 
are determined by (1) the character of the underlying formation, and 
(2) ruggedness of the terrain. The most prominent exposiu'es occur in 
mountainous areas underlain by hard, resistant rocks, and the poorest 
in low. rolling hills underlain bv soft, easilv weathered sediments. The 
area contains several types of natural vegetation whose distribution is 
determined by the following factors: (1) the character of the under- 
lying formation: (2) amount of residual soil; (3) steepness of slope; 
and {i} local climate. In general, steep rock\" slopes are covered by 
brush, and gentle slopes with a heavy soil mantle by grasses and annual 

The high rugged portion of the Santa Ynez Range east of Gaviota 
Canyon contains the best exiDOSures in the area mapped. Tilted sand- 
stone beds form prominent ledges, especially on the south slope. Shales 
are less prominently exposed, but have very little soil cover. Regardless 
of the underlying formation, this entire range is covered with a very 
dense impregnable chaparral-tA-pe brush, composed mainly of lilac, 
scrub oak. and other shrubs. 

In the lower portion of the Santa Ynez Range exposures are good 
on the rugged south slope west of Gaviota Canyon, but elsewhere are 
less prominent. Throughout this area brush, either the heavy chaparral 
type or low sage brush, grows only on hard, resistant formations such as 
sandstone, conglomerate, hard shales, and volcanic rocks. Clay shale 
formations and softer shales of the Monterey readily weather into a 
heavy adobe .soil which supports only gra.sses and annual herbs. Hard 
formations which fracture readily, such as Monterey cherty shale, are 
for the most part covered by live oak timber. Since the various types of 
vegetation are influenced by the underlying formations, their disti-ibu- 
tion is a great aid in mapping. 

The Purisima Hills are more or less covered with soil, but there 
are good local exposures. The vegetation is a mixture of three tyi^es, 
namely grasses and annual herbs, low brush, and live oak timber. The 
underlying formations have only slight influence on the distribution of 
these three ty|ies. In general, steep slopes are covered by brush, frac- 
tured shale areas by timber, and gentle slopes with deep soil, by grasses. 
In the western Purisima Hills north of Lompoc oil field is a very dense 
stand of scrub pine growing on Sisquoc diatomite. 

The low rolling San Rafael foothills are made up of loosely con- 
solidated gravels and clays of the Paso Robles formation and are covered 
with a thick soil mantle. Consequently there are few exposures. This is 
an area of grasslands, dotted vrith oaks. The same t.^i^e of vegetation 
prevails in the San Rafael Mountains, but with the addition of scat- 
tered digger pines. 



The earliest geological investigation in southwestern Santa Bar- 
bara County "was made by Thomas Antisell,^ who accompanied a party 
of engineers sent by the United States War Department to explore a 
route for a transcontinental railroad in 1856. 

The first geologic map and report published on the area were issued 
in 1907, after Arnold and Anderson mapped the geology of the Guada- 
lupe and old Lompoc quadrangles on the scale of 1 : 125,000.- This recon- 
naissance work covered all of the quadrangles except a part of the Santa 
Ynez Mountains. In 1925 the southwestern portion of the adjoining 
Santa Ynez quadrangle was mapped by R. Nelson.^ 

The geology of the western Santa Ynez Mountains was described 
briefly by Reed ^ and by Reed and Hollister.^ 

In 1943 Kelley ^ mapped and described in detail the Eocene section 
of Santa Anita Canyon area. 

No detailed information was published on the Santa Maria Basin 
until 1943, when the U. S. Geological Survey studied and mapped the 
stratigraphy of that area,'^ and also of the southeastern Purisima, Santa 
Rita, and Santa Rosa Hills. ^ The Survey has just completed a detailed 
study and map of the ground-water resources of Lompoc and Santa Ynez 

The Vaqueros fauna has been discussed by Loel and Corey ^° ; that 
of the Oligocene and Eocene by Arnold and Anderson, ^^ Woodring,^^ 
and Schenck and Kleinpell.^^ 

Geology of the Lompoc and Capitan oil fields has been described in 
California State Division of Mines Bulletin II8.1* 

I Antisell, Thomas, Geolog-ical report: Pacific Raih-oad Survey, vol. 7, pt. 2, chap. 
10, pp. 65-74, W^ashinpton, D. C, 1856. 

-Arnold, R., and Anderson, R., Geologv and oil resources of Santa Maria oil dis- 
trict, Santa Barbara County, Calif.: U. S. Geol. Survey Bull. .322, pp. 1-161, 1907. 

3 Nelson, R. N., Geology of the hvdrographlc basin of the upper Santa Ynez River, 
Calif.: Univ. California Dept. Geol. Sci. Bull., vol. 15, no. 10, pp. 327-396, 1925. 

* Reed, Ralph D., Geology of California, 355 pp., Tulsa, Oklahoma, Am. Assoc. 
Petroleum Geolog'ists, 1933. 

5 Reed, Ralph D., and Hollister, J. S., Structural evolution of southern California, 
pp. 86-97, Tulsa, Oklahoma, Am. Assoc. Petroleum (ieologists, 1936. 

8 Kelley, P. R., Eocene stratigraphy in western Santa Ynez Mountains, Santa 
Barbara County, California: Am. Assoc. Petroleum Geologists Bull., vol. 27, no. 1, 
pp. 1-19, 1943. 

^ Woodring, W. P., and others. Stratigraphy and paleontology of the Santa Maria 
district, California: Am. Assoc. Petroleum Geologists Bull., vol. 27, no. 10, pp. 1335- 
1360, 1943. . . . Geologic map of Santa Maria district, Santa Barbara County, Calif., 
U. S. Geol. Survey Oil and Gas Inv., Prelim. Map 14 (in 6 sheets), 1944. 

8"Woodring, W. P., and others, Geologj- of Santa Rosa Hills — eastern Purisima 
Hills district, Santa Barbara County, California: U. S. Geol. Survey Oil and Gas Inv., 
Prelim. Map 26, 1945. 

Upson, J. E., Thomasson, H. G., and others, Geology and water resources of Santa 
Ynez River vallev, Santa Barbara County, California : U. S. Geol. Survey dupUcate 
rept, pp. 1-322, June 1947. 

^0 Loel, W., and Corey, W. L., The Vaqueros formation, lower Miocene of Cali- 
fornia, I Paleontology: Univ. Cahfornia Dept. Geol. Sci. Bull., vol. 22, pp. 31-410, 1932. 

II Op. cit. 

12 Woodring, W. P., Upper Eocene orbitoid foraminifera from the western Santa 
Ynez Range, California, and their stratigraphic significance : San Diego Soc. Nat. Hist. 
Trans., vol. 6, no. 4, pp. 145-170, 1930. 

1* Schenck, H. G., and Kleinpell, R. M., The Refugian stage of the Pacific Coast 
Tertiary: Am. Assoc. Petroleum Geologists Bull., vol. 20, no. 2, pp. 215-225, 1936. 

i*Dibblee, T. W. Jr., Lompoc oil field: California Div. Mines Bull. 118, pp. 427- 
429, 1943. 

Kribbs, George R., Capitan oil field: California Div. Mines Bull. US, pp. 374-376, 


Physiographic Features 

The various physiograpliie features referred to within the quad- 
rangles mapped, and the principal streams to which reference is made, 
are shown on plate IB. Details of topography and drainage are shown 
on the topographic quadrangles. 

Santa Tjicz Mountains. The Santa Ynez Range is one of the east- 
ward-trending Transverse Ranges of southern California. It extends 
farther west than the other Transverse Ranges, paralleling the Santa 
Barbara channel on the south and extending continuously from Point 
Arguello eastward some 75 miles to Matilija Canyon in Ventura County. 
Only the western portion of the range is within the quadrangles mapped, 
where it is composed of two parts, the higher Santa Ynez Range, and the 
lower Santa Ynez Mountains. 

Referred to as the '"higher Santa Ynez Range" is the prominent 
mountain ridge extending eastward, unbroken from Gaviota Canyon 
beyond the area mapped into Ventura County. This mountain range was 
formed as a block uplifted along the Santa Ynez fault at its northern base. 
The course of this fault zone is marked by short rift canyons, saddles, or 
a sharp break in slope. South of the fault the range rises abruptly, form- 
ing a bold escarpment, to an even crest line averaging about 2500 feet 
elevation within Los Olivos quadrangle, but rising higher to the east. 
South of this crest the range slopes gently seaward. As the range is sculp- 
tured out of sedimentary formations dipping south, the crest is essen- 
tially a strike ridge ; the north flank is characterized by step-like topog- 
raphy and the south flank by dip-slopes. The drainage system is 
regular. Canyons on the north flank are short and steep, but on the south 
flank they are long, and the streams have reached grade and have 
developed small flood plains. 

The area referred to as the "lower Santa Ynez Mountains" com- 
prises the hills lying between the "higher Santa Ynez Range" and the 
Santa Ynez Valley, and extending westward to Point Arguello. The 
southern crest of these hills averages about 1400 feet elevation and 
extends from Las Cruces due west to the south side of Jalama Canyon. 
It is cut through by Santa Anita Canyon. This ridge is topographically 
and geologically the westward extension of the higher Santa Ynez 
Range, being similar in every respect, but on a smaller scale. From the 
head of Jalama Canyon another ridge branches off from the southern 
ridge and extends north of west through a high mass of hills to the 
prominent ridge of Tranquillon Mountain, which forms the main divide 
and backbone of the extreme western Santa Ynez Mountains. The drain- 
age system is somewhat irregulaj* because of complex geology. The Santa 
Rosa Hills average about 1600 feet elevation and form the northern crest 
of the lower Santa Ynez Mountains. This ridge extends from Salsipuedes 
Creek eastward to Nojoqui Creek. The hills extending westward and east- 
ward from the Santa Rosa Hills are cut through by several major north- 
ward trending canyons antecedent to them. The Santa Rita Hills are 
geologically part of the Santa Rosa Hills but are separated by the Santa 
Ynez River which forms an antecedent canyon between them. 

San Fafael Mountains. The San Rafael Mountains average about 
4000 feet elevation and form the most southerly of the northwest-trending 
Coast Ranges. Only a very small portion of the southwest flank lies within 


Los Olivos quadrangle. The slope is steep, and as it is made up of serpen- 
tine and Franciscan rocks, it is characterized by numerous landslides. 
The range has been thrust up along the Little Pine fault, which is marked 
by an abrupt change in slope between the mountains on the upthrown 
side and the San Rafael foothills to the southwest. 

San Bafael Foothills. Referred to as the San Rafael foothills is the 
broad area of low rolling hills southwest of the San Rafael Mountains. 
They are the result of gentle anticlinal uplift, and since they are made up 
of soft formations they are characterized by low, rounded ridges of more 
or less equal height, and canyons which have reached grade. These hills 
are cut through by the major canyons, antecedent to them, draining south- 
westward from the San Rafael Mountains. 

Purisima Hills. The Purisima Hills are an anticlinal uplift. Their 
main crest averages about 1500 feet elevation, and trends about N. 75° W. 
They extend into the Santa Maria quadrangle on the northwest where 
they merge into Burton Mesa on the west. The crest is located about mid- 
way between the northern base and the southern base except in the west- 
ern portion, where it approaches the latter. The hills are of moderate 
relief. The drainage pattern is normal for an area of anticlinal uplift, 
with consequent canyons cut do\\ai each flank. The streams have reached 
grade and have developed small flood plains. The southeast end of the 
Purisima Hills is cut through by the antecedent canyon of Zaca Creek. 

Santa Yn ez Y alley. The Santa Ynez Valley is a synclinal area which 
has undergone little or no uplift. It is separated by the southeast end of 
the Purisima Hills just north of Solvang into an upper or northeastern 
portion, and a lower or southwestern portion. 

The upper Santa Ynez Valle}' is a broad, roughly triangular valley 
with an average elevation of 700 feet. It is essentially a structural trough, 
but the southern portion has been formed by lateral stream erosion. 
Streams do not follow this valley but drain southward across it into the 
Santa Ynez River at its southern edge. Some of these have cut below the 
original valley surface, indicating slight uplift. The river has cut several 
terraces and a small flood plain down to an elevation of some 500 feet. 
Geologically the upper Santa Ynez Valley is a synclinal trough extending 
through Los Olivos northwestward through a gap between the Purisima 
Hills and San Rafael foothills into Los Alamos Valley. 

The lower Santa Ynez Valley averages about 350 feet elevation and 
is a synclinal trough between the eastern Purisima Hills and the Santa 
Ynez Mountains. This portion is followed by the Santa Ynez River 
which has destroyed the original valley surface and formed a flood 
plain. About 6 miles west of Buellton the river leaves this valley and cuts 
south between the Santa Rosa and Santa Rita Hills; but the synclinal 
trough continues westward through Santa Rita Valley, where the 
original depositional surface has been elevated and warped, but is still 
preserved locally. The Santa Rita Valley is at an elevation of about 600 
feet and is separated by Ioav saddles from Santa Ynez and Lompoc 

Lompoc Yalley. Lompoc Valley is geologically the westward exten- 
sion of the lower Santa Ynez Valley synclinal trough, but is consider- 
ably broader. It has undergone slight uplift and erosion, so that the 
original sand}^ surface has been broadly warped and preserved only in 
the northeastern and southwestern portions, at an average elevation of 


300 feet. The Santa Ynez River has cut throug'h tliis sandy valley and has 
formed a flood plain, referred to as ' ' Lompoc Plain ' ' by Upson/^ about 
2 miles wide and about 11 miles long at an elevation of less than 100 feet. 

Burton Mesa. To the northwest, Lompoc Valley blends into a low 
mesa-like area known as Burton Mesa, which averages about 400 feet in 
elevation. This is an uplifted peneplain locally dissected by youthful 

Coastal Terraces. At least three wave-cut terraces are developed 
along the coast. The lowest occurs throughout the coast at an elevation of 
50 to 150 feet. It forms a broad but much dissected coastal plain north 
and east of Point Conception, and also near Point Arguello. A higher 
terrace, at an elevation of about 200 feet, is well developed against 
Burton Mesa, but is preserved only as small remnants elsewhere. Isolated 
remnants of a still higher terrace occur at an elevation of about 500 feet 
on the seaward slopes of the hills northeast of Point Conception and 
Point Arguello, and also near Alegria and Refugio Canyons. 


The drainage systems within each physiographic province have 
been described. With the exception of the north flank of the Purisima 
Hills which drains into Los Alamos Valley, the entire area north of the 
crest of the Santa Ynez Mountains is drained by the Santa Ynez River 
system. All tributaries gather into this river which flows west into the 
ocean at Surf. The river generally follows the Santa Ynez-Lompoc 
Valley synclinal trough, but in many places cuts south of it into the 
foothills of the Santa Ynez Mountains. The general drainage system is 
shown on plate IB. 

During heav.y rainy seasons the Santa Ynez River carries consider- 
able runoff. The river generally runs throughout the year, but drys up 
locally during prolonged dry seasons. Other streams are intermittent, 
but some of the major streams in the Santa Ynez Mountains run 

throughout the year. ''4a4m^rr?4jtaai£a 

Springs are abundant in the Santa Yn^^Sp^,F:ji^^>a;^J- 
some occur in the Purisima Hills, and a If^Y. ' '^ ^'^'^^'^Hu^l^ 
The valleys are generally devoid of spring . -pt Jw,^^k 
artesian spring at Santa Ynez. 

Erosion Cycles 

Southwestern Santa Barbara County has been through at least two 
cycles of erosion during the Pleistocene. The first cycle occurred during 
middle Pleistocene time prior to deposition of the middle or upper 
Pleistocene Orcutt sand ; the second took place during late Pleistocene. 

During the first cycle, Burton Mesa, Santa Rita Hills, and the hills 
north of Canada Honda were peneplained ; the lower Santa Ynez Moun- 
tains, Purisima Hills, and San Rafael foothills were probably reduced to 
late maturity or an old-age stage of erosion. This erosion surface is pre- 
served in the western and southeastern Purisima Hills, but elsewhere 
there are onlj^ small remnants. Hills which once occupied the vicinity of 
Solvang and Santa Ynez were peneplained to form the southern part of 
upper Santa Ynez Valley. This erosion period was followed by filling of 
Lompoc, Santa Ynez, and Los Alamos Valleys by sand of the Orcutt 
formation and terrestrial gravels. 

IS Op. cit 


The second cycle was inaugurated by renewed uplift of the entire 
region by compressive forces. The mountains and hills were uplifted 
to their present heights, thereby causing a renewed downcutting of 
canyons by streams. The peneplained surface of Burton and the 
hills north of Cafiada Honda were elevated at this time, and were partly 
dissected by youthful streams. Lompoc and Santa Ynez Valleys were 
likewise raised but to a lesser amount than the adjacent highlands, and 
the Santa Ynez River deepened its channel. Regional uplift during the 
second cycle was recurrent in three or four stages, as indicated by that 
many terraces along the Santa Ynez River valley, and also by at least 
three wave-cut terraces along the coast. 

The final stage of the second cycle, at the close of Pleistocene or 
beginning of Recent time, was marked by lateral erosion by streams to 
form flood-plains in their respective valleys or canyons. During this 
stage the Santa Ynez River developed the flood-plain of lower Santa 
Ynez Valley, and the broad, level plain of Lompoc Valley. The level 
portion of Los Alamos Valley was also formed by lateral stream erosion. 
As, or after, these flood-plains were formed the flat lower valleys became 
filled with terrestrial alluvium. This was followed, or possibly accom- 
panied, by regional subsidence, or rise of sea level, of about 300 feet 
maximum, which caused the lower parts of the alluviated flood-plains 
to be submerged below sea level ; but they were not drowned, as deposition 
of alluvium apparently kept pace with subsidence. However, in higher 
areas away from the sea most streams are deepening their channels 
through the alluvium, indicating slight recent uplift of these areas. 

The southwestern portion of Santa Barbara County is an excellent 
example of an area in which all physiographic features are the direct 
result of uplift by compressive forces active during Quaternary time, a 
condition general throughout the Coast Ranges of California. In general, 
the amount of relief is proportional to the amount of uplift. The highest 
areas, such as the Sau Rafael and higher Santa Ynez Ranges, have under- 
^e8.e"th^ ^^iSt^BtjiRiW^iilltJ -of uplift, having been elevated along major 
■"""'"*""" i^^fp^fik^W'^Wpintiatnre stage of erosion, being characterized 
JiffA/^-Sliii^'fed canyons. The hilly areas, such as the lower 
ff^!ri'sTTL'urisima Hills, and San Rafael foothills, have 
midergone moderate uplift, mainlj^ by compressive folding. They are in 
the middle to late mature stage of erosion, being characterized by 
rounded crests and canyons with small flood plains. The valleys are 
synclinal troughs between the uplifted areas. They have been raised only 
slightly and have been subjected to comparatively little erosion. 

The submerged area adjacent to the Santa Ynez Mountains has 
undergone relatively little uplift as compared to the land area. This is 
indicated by the fact that only the youngest formations of the range, 
namely, the Sisquoc and Montere^^ formations, crop out along the coast, 
and generally dip seaward, indicating relative uplift of the land area. 
The sea is constantly eroding landward, and in the vicinity of Point 
Arguello and east of Gaviota the waves have cut through the Sisquoc 
into the more resistant Monterej' shale. Point Arguello and Point Con- 
ception are essentially anticlinal uplifts exposing resistant Monterey 
shale, forming points jutting out into the sea to make right-angle bends in 
the coast line. Aside from these two prominent points, the coast line is 
fairly straight, indicating that the mature stage of the wave erosion 
cycle has been reached. 


Franciscan Formation 

The Franciscan formation of Santa Barbara County is typical of 
that found elsewhere in California, being composed of sandstone, clay 
shale, radiolarian chert, and basalt, of Upper Jurassic ( ?) age. It is the 
oldest formation in the county and forms the so-called ' ' basement upon 
which vounger formations were laid down. 

The Franciscan is widely exposed along the southwest slope ot the 
San Rafael Mountains, of which a small portion was mapped m the north- 
east corner of Los Olivos quadrangle. An exposure of clay shale mapped 
as the Honda shale in the extreme western Santa Ynez Mountains may 
be a member of the Franciscan. Both exposures are intruded by serpen- 
tinous rocks. Wells drilled on Burton Mesa and in the Lompoc oil field 
encountered the Franciscan below the Miocene formations. 

In the San Rafael Mountains the various members of the Franciscan 
strike due east to N. 60° ^Y., and generally dip steeply north. However, 
the rocks are so highly sheared and brecciated, and injected by numerous 
masses of serpentine, that the sequence could not be worked out. lie 
Franciscan here is composed of four rock types, sandstone, clay shale, 
varicolored chert, and basalt. 

The sandstone is bluish green when fresh but weathers brown; it is 
more or less medium grained, arkosic, and is composed of angular grams 
mainlv of feldspar. It is massive and hard, but closely jointed so that it 
does not form prominent outcrops. ]\Iuch of it contains calcite vemlets. 
It forms poor exposures and is generally the only rock m the Franciscan 
which supports brush. , ^ • i 

The clav shale is dark brownish green to black and is nearly every- 
where in a very highlv sheared and brecciated condition. As a result it 
seldom crops out, but instead forms a deep clayey adobe soil which sup- 
ports grass. It forms numerous landslides. 

The varicolored cherts occur as irregular lenses, most ot them less 
than 50 feet thick, composed of individual layers averaging 2 or 3 inches 
in thickness of maroon red and light green siliceous chert, separated by 
thin partings of shale. The chert lenses are generally much contorted or 
locallv brecciated. They form rather prominent outcrops ^ 

The so-called "basalt" is a very dense to amygdaloidal extrusive 
rock It locallv shows pillow structure, indicating that it was extruded 
under water. The rock is drab green, but weathers brown ; it is massive, 
hard, but not heavv, and is rather closely jointed. It is more or less 
altered to greenstone, and contains numerous vemlets of calcite. it is 
the most resistant rock of the_ Franciscan, as it forms prominent out- 
crops ; large masses form conspicuous knobs. 

In the San Rafael T^Iountains the Franciscan formation is cut by 
numerous sill-like masses of 'serpentine. This was intruded as an ultra- 
basic rock such as peridotite or pyroxenite, then altered to serpentine 
by hvdrothermal action. The peridotite rocks have been more or less com- 
pletelv altered to serpentine ; but where the original rock was pyroxenite, 
manvof the crvstals of pyroxene are partially preserved. The serpentine 
is dark green to bluish green and contains numerous shmy slickensided 
surfaces resulting from expansion during chemical alteration. Much of 
it is brecciated, and tends to form landslides. These bare, slickensided 
green exposures of serpentine are generally devoid of vegetation. 


In addition to the San Rafael Mountain exposures, there is a large 
outcrop of serpentine at the head of San Pascual Canyon in the extreme 
western Santa Ynez Mountains. This exposure is made up largely of 
serpentinized pj^roxenite. Serpentine also occurs in San Lucas and Wons 
Canyons as small exposures, where it seems to inject shales of the Espada 

Honda Formation 

The Honda formation consists of several thousand feet of clay shale 
exposed only in the extreme western Santa Ynez Mountains at Canada 
Honda, from 1 mile to 4 miles east of Point Pedernales. 

The Honda formation is composed of dark greenish-brown clay 
shale commonly containing buff-weathering calcareous concretions. It 
locally contains thin layers of fine-grained sandstone of the same color. 
The shale is poorly bedded and is everywhere intensely sheared. The 
Honda shale either overlies or is intruded by serpentinized pyroxenite to 
the north, and is unconformably overlain by the Espada formation. 

A small indeterminate species of Ancella was found in the northern- 
most exposure of Honda shale in San Pascual Canyon. The Honda shale 
may be equivalent to the type Knoxville, but its highly sheared condition 
and unconformable relationship with the Espada formation suggests that 
it may be a shale member of the Franciscan. Since neither could be 
proved, it is designated by the local name Honda. The type locality is on 
the north side of Caiiada Honda 3 miles east of Point Pedernales. 

Espada Formation 

The Espada formation is a thick series of dark greenish-brown 
sandy shales of predominantly Lower Cretaceous age exposed at several 
areas on the north side of the Santa Ynez Mountains. 

The type locality of the Espada formation is designated as the 
south side of Canada Honda about 3 miles east of Point Pedernales, 
where it is well exposed. Other exposures occur in Salsipuedes and El 
Jaro Canyons, Nojoqui and Alisal Canyons, and in San Lucas and Wons 

In all exposures the Espada formation is a monotonous series of 
dark greenish-brown, thin-bedded silty shales and a lesser amount of 
thin interbeds of hard fine-grained sandstones. Crude rhythmic bedding 
is general throughout. The Espada formation is characterized by its pre- 
vailing dark greenish-brown color in the shales and sandstones alike, 
and by the abundant black specks of carbonaceous material in parting 
planes. Locally the Espada contains thin lenses of conglomerate with 
well-rounded pebbles of black chert. 

The Espada formation is well indurated and is well exposed in 
creek beds. It forms dark-brown exposures in hills which are invariably 
covered by brush. 

Unfortunately no complete section of the Espada formation is 
exposed at any one locality. At the type locality at Caiiada Honda, the 
base is well exposed. Here it consists of 1 foot to 5 feet of dark brown con- 
glomeratic sandstone resting unconformably on highly sheared clay shale 
of the Honda formation. This conglomerate is overlain by about 4000 feet 
of dark greenish-brown shale and thin hard sandstone as described above. 
The Espada here is unconformably overlain by lower Miocene beds. 


In Sail Lucas and Wons Canyons a masimnm thickness of 6800 feet 
of Espada formation is exposed, but the base of the section is in fault or 
intrusive contact with serpentine, and the top is unconformably over- 
lain by Eocene and middle Miocene beds. The relationship of the Espada 
to the Upper Cretaceous Jalama formation is not definitely known, but 
these are believed to be in contact at only two localities : at the head of 
Salsipuedes Cam-on. where the relationship appears to be an uncon- 
formity, and at Nojoqui Canyon, where shales of the Espada formation 
are in conformable contact with hard sandstones and dark-gray shales 
believed to be the Jalama formation. 

The Espada formation in the Santa Ynez Mountains is generally 
known as the "Knoxville" formation by geologists who have worked in 
the region. In San Lucas Canyon " AuceUa" crassicollis was found in 
the upper portion. This places at least part of the Espada formation in 
the Lower Cretaceous, equivalent to the Paskenta formation of Sacra- 
mento Yalley." Aucella" piochii was found in shales similar to the Espada 
in the Casmalia Hills and in the San Rafael Mountains. This indicates 
Upper Jurassic age. equivalent to the tv^pe Knoxville at Sacramento 
Valley. The Espada formation is lithologically and fauiially indivisible, 
but it probably contains strata equivalent to the type Knoxville (Upper 
Jurassic), type Paskenta (LoAver Cretaceous), and possibly the type 
Horsetown (middle Cretaceous). Because of lack of faunal control, the 
formation is here designated hy the local name Espada. 

Jalama Formation 

The Jalama formation consists of about 4000 feet of clay shales and 
sandstones of Upper Cretaceous age overlying the Espada formation and 
disconformably overlain by the Eocene Anita shale. The Jalama forma- 
tion is exposed in the Santa Ynez Mountains at Santa Anita and Jalama 
Canyons, and at the head of Salsipuedes Canyon ; in Ytias and Xojociui 
Canyons ; and on the north flank of the higher Santa Ynez Range between 
Gaviota Pass and Quiota Canyon. 

The type locality of the Jalama formation is designated as the divide 
between Santa Anita and Bulito Canyons. Here the section is as follows : 

Anita shale (middle Eocene) 

Disconf ormity (?) 

Gray-white to buff, hard, thick-bedded to massive well-sorted fine to 
locally medium-grained saudsitone ; minor iuterbeds of sandy silt- 
stone. Carries Trigonia, Baculites 300 ft. 

Brown-gray massive to poorly bedded highly micaceous siltstone and silty 

claystone 1000 ft. 

Light buff, hard, well-bedded fine-grained sandstone ; minor interbedded 
clay shale ; lower 3 feet contains abundant rounded pebbles of 
porphyritic volcanic rocks and of Franciscan red and green chert. 
Contains several fossil reefs of Calva steinyi, Trigonia 200 ft. 

Dark-gray well-bedded clay shale with subspheroidal fracture 800 ft. 

Light-brown very hard fine-grained sandstone and interbedded clay shale 

as above 150 ft. 

Dark gray-brown well-bedded clay shale, slightly carbonacous 400 ft. 

Total thickness of Jalama formation exposed 2850 ft. 

Pacifico fault 

The above sequence holds true for tlie Jalama formation in Jalama 
Canyon, and also in the higher Santa Ynez Range south of Alisal ranch. 


The relationship to the overlying Eocene Anita shale is accordant, with 
no evidence of erosion. However in the Santa Rosa Hills the Jalama is 
overlain by the Anita shale and Sierra Blanca limestone with an angnlar 
unconformity of about 15°. At the mouth of Ytias Creek an angular 
nnconformity occurs above the Jalama, but Upper Cretaceous Trigonias 
occur above the unconformity. These beds are in turn conformably 
overlain by the Matilija sandstone. 

At Santa Anita and Jalama Canyons the Jalama formation is highly 
fossilif erous and has yielded a large fauna. Of these, the following occur 
abundantly : 


Calva steinyi (Hawley) (= Venus steinyi Hawley) 

Glycymeris veatchii var. major Stanton 

Inoceramus sp. 

Mactra ashburnerii Gabb 

Trigonia evansi Meek 

Trigonia gibboniana Meek 

Volutadernia cf. gabbi White 

Baculites sp. 

These forms place the Jalama formation in the Upper Cretaceous, 
and correlate it with the Panoche formation of San Joaquin Valley and 
possibly with the Chieo formation of Sacramento Valley. 

The Eocene-Oligocene Series 

The Eocene and lower Oligocene series is exposed only in the Santa 
Ynez Range and consists of a very thick conformable series of marine 
sandstones and shales totaling 9000 feet in the higher Santa Ynez Range 
eastward from Gaviota Canyon, 6000 feet westward from Gaviota 
Canyon, and thinning considerably on the north flank. It has been 
mapped previously as the Tejon formation. 

The Eocene-Oligocene series has been subdivided into five lithologic 
units mappable throughout the western Santa Ynez Range. They are, 
starting with the lowest, Anita shale, Matilija sandstone. Cozy Dell shale, 
Sacate formation, and Gaviota formation. The lower Oligocene Gaviota 
formation is confined to the western Santa Ynez Range. The four Eocene 
units are the same lithologic units as those recognized in the eastern Santa 
Ynez Range as brought out by areal mapping of the whole range. The 
Anita shale of the western portion corresponds to what is called in unpub- 
lished reports the Juncal formation of the eastern Santa Ynez Range, and 
the Sacate formation corresponds to the ' ' Coldwater ' ' sandstone in the 
eastern Santa Ynez Range. The names Matilija and Cozy Dell have been 
retained. The type localities of both are in Matilija Canyon, Ventura 
County. All four of these units can be traced westward to San Marcos 
Pass, where all but the "Coldwater" dip under a cross-syneline, but 
reappear to the west. It must be emphasized that these formations were 
mapped throughout the Santa Ynez Range as lithologic, not as time units, 
and that their boundaries are not everywhere contemporaneous. Some 
units are difficult to differentiate locally, but their lithologic character is 
fairly persistent. 

As the name ' ' Coldwater ' ' is preoccupied twice in American liter- 
ature, Kelley ^^ proposed the name Sacate for the ' ' Coldwater ' ' forma- 
tion in the western Santa Ynez Range. 

I Op. cit, p. 10. 


The Sacate-Gaviota problem is one difficult to solve. The Gaviota 
formation has been separated from the Saeate in the western Santa Ynez 
Range because of its distinct faunal content, but it is lithologically nearly 
simitar to the Saeate. The contact has been designated by a faunal break 
and slieht litholoeic change at the type area of the Gaviota formation 
on the south flank of the range. On the north flank the two are difficult 
to separate and are therefore mapped together as Sacate-Gaviota. 

Eocene at Wons Canyon 

On the east side of Wons Canyon, on the east edge of Los Olivos 
quadrande. about 1600 feet of Eocene sediments lie unconformably on 
the Espada shale and are unconformably overlain by the upper [Monterey 

Q It £3 I P 

The Eocene mapped as Anita shale in "SVons Canyon consists of dark- 
crrav siltstone and fine nodular sandstones ranging in thickness from less 
than 1 foot to 300 feet. The Matilija comprises about 200 feet of cobble 
conglomerate composed of weU-rounded cobbles of quartzite and acidic 
ic^neous rocks in buff sandstone matrix, overlain by about 500 feet of 
medium-grained buff sandstone which grades upward into a fine-grained 
greenish-brown nodular sandstone about 500 feet thick. 

[Molluscan fossils occur in the nodular sandstones near the base 
of the Anita shale and also in the upper nodular sandstones of the 
:\ratilija. Both localities have yielded TurriteUa uvasana, Ostrea tdnaen- 
sis Gabb, and Galeodea sp. 

Sierra Blanca Limestone 

The Sierra Blanca limestone is well developed at the base of the 
Eocene section in the San Rafael :\Iountains where it was named and 
described by Xelson.i" ^^^ Keeuan.^s j^ the Santa Ynez Mountains it 
occurs at onlv three localities. 

The most prominent exposure of Sierra Blanca limestone occurs m 
Xojoqui Canvon at Live Oak Ranch dair^-. Here it consists of about 50 
feet of grav-white. hard, sandv. algal limestone. It extends up both sides 
of the ean'von to the west, where it rests with a well-exposed angular 
unconforniitv on the Jalama formation. This basal limestone extends up 
the ridge south of the canyon for some 2 miles before it lenses out to the 

west . 

A small lens of Sierra Blanca limestone as much as 20 feet thick and 
a quarter of a mile long occurs on the south side of Jalama Canyon 1^ 
miles southeast of the point where the road enters the canyon from the 
north. Here it occurs in the Anita shale about 250 feet below the top. It 
is of the same character as the Xojoqui Canyon exi^osure and contains' 
abundant orbitoidal foraminif era.^^ . . 

At Los Sauces Creek. 1 mile south of Tranquillon [Mountain, a thm 
lens of Sierra Blanca limestone -o overlies buff sandstone (Eocene ?) 
which rests on the Espada formation. The limestone here contains abund- 
ant orbitoidal f oraminif era. 

i Keenan M F The Eocene Sierra Blanca limestone at the t>-pe locality in Santo 
Barbar^CoXV California: San Diego Soc. Xat. Hist. Trans., voL 7. no. 8. pp. d3-84. 

^^^^" "For a description of the foraminifera see Woodring, W. P., op. cit 1930. p. 157, 

P'- ^ 'a) For a description see Woodring, W. P., op. cit. 1930, p. 157. 


The following species of orbitoidal foraminifera occur in the Sierra 
Blanca limestone at Jalama Canyon : 

Discocyclina psila Woodring 
Aetinocyclina aster Woodring 
Olicrculina or Nuinnuilites 

On the west side of Ramajal Canyon north of Jalama Creek a sandy 

phase of the Sierra Blanca limestone carries the following molluscs: 

"Macrocallista" conradiana ? Gabb 
Amaurellina inezana Conrad 

The Sierra Blanca limestone is assigned to the middle Eocene. 

Anita Shale 

The Anita shale consists of about 1000 feet of clay shale lying above 
the Jalama formation and below the Matilija sandstone. It has been 
named and described by Kelley;^^ the type locality is on the south side 
of upper Santa Anita Canyon. 

The Anita shale in the western Santa Ynez Mountains consists of 
dark-gray moderately well bedded clay shales and some thin beds 
of greenish-brown highly micaceous sandstone. At Santa Anita Canyon 
the middle portion contains thin calcareous sandstone beds with orbi- 
toidal foraminifera. About 30 feet of highly foraminiferal red and green 
clay shale, known as the "Poppiu shale," occurs from 200 to 400 feet 
below the top of the Anita. The red and green colors are due to iron oxides, 
which occur in large quantities. This colored shale commonly contains 
calcite veinlets. 

The Anita shale is about 1000 feet thick at Jalama and Santa Anita 
Canyons, and also in the higher Santa Ynez Range. On Santa Rosa Ridge 
it thins to about 300 feet, and to the north it buttresses out. It thins out 
likewise in Jalama and Salsipuedes Canyons and in Caiiada Honda. 

The relationship of the Anita shale to the overlying Matilija sand- 
stone is accordant, although Kelley ^^ reports a disconformity. The rela- 
tionship of the Anita shale to the underlying Jalama formation appears 
to be conformable, but in the northerly exposures the Anita rests uncon- 
formably on the Jalama or older formations. The iron oxides in the 
Poppin shale were probably derived from basic rocks of the Franciscan 
to the north. The Poppin shale and Sierra Blanca limestone in Jalama 
Canyon occur at about the same horizon in the Anita shale, and it is 
possible that this horizon may be the base of the Eocene section of the 
Santa Ynez Range. 

The upper portion of the Anita shale, especially the Poppin shale, 
has yielded a large foraminiferal f auna.^^ On the basis of this fauna, and 
of the occurrence of the Sierra Blanca limestone at about the same horizon, 
the upper Anita shale is assigned to upper middle Eocene. The lower 
portion of the Anita shale has yielded no foraminifera, and its age is 
therefore unknown. It may be middle or lower Eocene or Upper Cre- 

Matilija Sandstone 

The Matilija sandstone in the w^estern Santa Ynez Mountains con- 
sists of about 1000 feet of sandstone lying conformably between the Anita 
shale below and the Cozy Dell shale above. 

21 Op. cit, p. 6. 

22 0p. cit, p. 7. 

23 For listing, see Kelley, F. R., op. cit., p. 8. 


The Matilija sandstone attains a maximum thickness of about 1200 
feet in the higher Santa Ynez Kan?e east of Las Cruces, but thins down 
to about 400 feet at Refugio Pass, then thickens eastward to 2000 feet at 
Santa Ynez Peak. Between Las Cruces and Jalama Canyon the Matilija 
is from 500 to 1000 feet thick. Northward it thins rapidly, being less than 
300 feet thick in the Santa Rosa Hills and in areas to the west. Where the 
underlying Anita shale buttresses out the Matilija sand rests unconform- 
ably on the Cretaceous or Franciscan. o- ^ . ^i • i 

The ^latilija is made up of a succession of beds up to 2o feet thick 
of massive, medium-grained fairly hard bluish-white sandstone which 
weathers buff. The sandstone beds are separated by thm partings ot 
micaceous sandv shale. The basal portion locally contains an algal reet 
and some rounded cobbles of quartzite and granitic rocks. 

The Alatilija sandstone is highly resistant to erosion and forms the 
highest strike ridges of the western Santa Ynez Mountains. Most of it 

supports brush. . , . n o, ^ t^ tt-h 

At the Gaviotito-Santa Anita divide and also m the Santa Rosa Hiiis 

the Matilija has yielded the following diagnostic moUuscs : 


Macrocallista horuii Gabb 

Gari horuii (Gabb) 

Xemocardium linteum (Conrad) 

Pitar uvasanus (Conrad) 

Schedocardia ef. brewerii (Gabb) 

Amaurellina aff. moragai (Stewart) 

Ectinocbilus canalifer supra plica tus (Gabb) 

Ficopsis horuii (Gabb) 

Ficopsis remondii (Gabb) 

Ficus mamillatus ((iabbj 

Galeodea susanae (Schenck) 

Olequahia ef. horuii (Gabb) 

Seraphs erratica Cooper 

Turritella uvasana Conrad 

Turritella applinae Hanna 

Turritella scrippseusis M. A. Hanna 

This fauna places the Matilija sandstone in early upper Eocene, or 
in the so-called moUuscan " Transition stage" of Clark and Vokes.- 

Cozy Dell Shale 

In the western Santa Ynez Range the Cozy DeU shale consists of 
about 700 feet of well-bedded shale lying conformably on the Matilija 
sandstone and grading upward into the Sacate formation 

The Cozy DeU shale maintains a fairly uniform thickness ot about 
700 feet throughout the western Santa Ynez Mountains, although it is 
somewhat thicker in the higher Santa Ynez Range. „ ^ -, , -, , ^ 

The lower half of the Cozv Dell shale consists of well-bedded, but 
easily weathered grav clay shales with spheroidal fracture. This portion 
contains one, or loeallv several, thin beds of hard greenish sandstone IbO 
feet from the base. The upper half of the Cozy Dell consists of the same 
tvpe of shale but with two members of thin-bedded, slightly siliceous 
harder brown clav shales which weather pale gray and form prominent 
exposures The upper member locally carries gray limestone nodules 
that weather vellow. The Cozy Dell shale grades upward through a series 
of thin sandstone interbeds into the overhdng Sacate sandstone. 

^cTark, B. K. and Yokes. H. E., Summary of marine Eocene sequence of western 
North America : Geol. Soc. America Bull., vol. 47, no. 6, pp. 80I-8 < 8, I9rft>. 


The Cozy Dell sliale is nou-resistant to erosion, forming saddles 
across ridges or amphitheaters in canyons between more resistant Matilija 
and Saeate sandstones. It forms grassy slopes. 

The lower half of the Cozy Dell shale has yielded an upper Eocene 
foraminiferal fauna. The species listed by Kelley ^^ correlate it with 
Laiming's zone A-2.-" The upper half of the Cozy Dell shale has not 
yielded a diagnostic fauna. 

Saeate ("Coldwater") Formation 

In the western Santa Ynez Mountains the Saeate (or "Coldwater") 
formation consists of about 1000 feet of interbedded sandstone and shale 
conformable between the Cozy Dell shale below and the Gaviota forma- 
tion above. The type localit}^ of the Saeate formation is at Saeate Can- 
yon ; this section is described by Kelley .^^ 

The Saeate formation consists of sandstone and shale interbedded 
in about equal amounts. The sandstone beds are fine to medium grained, 
hard, well bedded to massive, highly micaceous, bluish gray when fresh, 
but weather to buff. The hard thin beds form large slabs. The inter- 
bedded shales are gray, w^ell bedded to laminated, highly micaceous, 
sparingly foraminiferal. Thin layers of hard brown conglomerate occur 
locally, with rounded pebbles of porphyritic igneous rock and some Fran- 
ciscan red cherts in a hard sandstone matrix commonly containing 03'ster 
shells. The uppermost 200 to 500 feet of Saeate on the south flank of the 
range consists of brown slightly organic massive to w^ell-bedded clay 
shale. On the south flank the Saeate formation is well exposed. Here 
the hard sandstone beds form prominent ledges. 

Both the upper and lower contacts of the Saeate formation are gra- 
dational and thus difficult to map. The base is placed at the first appear- 
ance of numerous sandstone beds w^hieli form a prominent topographic 
break. West of Las Cruces the top is placed at the contact between the 
organic shale member below, which carries an Eocene fauna, and the 
massive, poorly exposed siltstone above, which carries a Refugian fauna 
and is therefore assigned to the Gaviota formation. East of Gaviota 
Canyon this siltstone grades laterally into sandstone, so that all of the 
500 feet of shale there underlying the Gaviota sandstone is mapped 
with the Saeate. 

In the Santa Rosa Hills and San Julian Ranch the Saeate is pre- 
dominantly shale with thin sandstone interbeds. It grades upward into 
the Gaviota formation which is mainly sandstone, but because of poor 
exposures and lack of faunal control, the contact has not been determined. 
The formations are therefore mapped together as Sacate-Gaviota. 

The Saeate formation carries the following megafossils : '^^ 


Venericardia cf. hornii (Gabb) 

Ostrea idriaeusis Gabb 

Amaurellina sp. 

Cypraea sp. 

Turritella variata var. julian.-i Merriam 

^ Op. cit., p. 11. 

28 Kelley, F. R., op. cit, p. 10. 

27 Op. cit, pp. 10-12. 

28 Kelley, P. R., op. cit, p. 13. 


This meager fauna and the stratigraphic position of the Sacate 
formation place it in uppermost Eocene, equivalent to Clark and Vokes' 
niolluscan "Tejon stage." The Sacate has yielded a foraminiferal fauna 
correlative with Laiming's zone A-1. 

Gaviota Formation 

The Gaviota formation consists of about 1600 feet of thick-bedded 
sandstone and siitstone conformable between the Sacate formation below 
and the Alegria sandstone above. The type area of the Gaviota forma- 
tion is on the south slope of the Santa Ynez Range between Gaviota and 
Bulito Canyons ; the type locality is at Caiiada de Santa Anita.-'' 

The type Gaviota formation west of Las Cruces is about 1600 feet 
thick and consists of three members, each about 500 feet thick. The lower 
member is a massive soft gray siitstone; the middle member is light 
buff, thick-bedded, well-sorted fine- to medium-grained concretionary 
sandstone; the upper member is gray sandy siitstone with some inter- 
bedded fine-grained sandstone. On the south flank of the range east of 
Gaviota Canyon, and on the north flank of the Santa Ynez Mountains, 
the upper member grades into sandstone; east of Tajiguas Canyon the 
lower member also becomes sandstone. The sandstones of the Gaviota 
formation are highly resistant to weathering and thus form prominent 
brush-covered outcrops. The siitstone members are easily weathered to 
low grassy slopes. 

The Gaviota formation is of shallow marine origin, and the sand- 
stones are richly fossiliferous. A prominent fossil reef composed largely 
of Crassatella collina occurs at the top of the middle member near Las 
Cruces and near the San Julian ranch house. Foraminif era are abundant 
in the siitstone members. 

The f ollo-s^-ing molluscs are abundant in the Gaviota formation : 


Crassatella collina Conrad 

Ostrea tayloriana Gabb 

Pecten (Cblamys) yneziana Arnold 

Tivela inezana Conrad 

"Cardium brewerii" Gabb (large, of Arnold & Anderson 1907) 

Yenericardia hornii Gabb 

Turritella variata Conrad 

Ficus gesteri Wagner & Schilling 

Siphonalia merriami Wagner & Schilling 

Venericardia liornii has been regarded as an Eocene marker, but the 
rest of the molluscan fauna is unlike that of any other Eocene fauna of 
California. The foraminiferal fauna is also unlike that of the California 
Eocene. Because of the strange fauna Schenck and Kleinpell^" desig- 
nate the Gaviota formation at the type locality as the type "Refugian 
stage," which they assign to lower Oligocene. 

Bed by bed mapping of the Gaviota formation on the south slope 
of the Santa Ynez Range from Gaviota Canyon eastward to San jVIarcos 
Pass shows that the upper portion grades laterally eastward through 
coarse littoral sands into the basal pink conglomerate and red beds of the 
lower part of the Sespe formation, the contact becoming successively 
lower from west to east. The lower portion of the Gaviota sandstone 

»Efflnger, W. L., Gaviota formation of Santa Barbara County, California: Geol. 
Soc. America Proc. 1935, pp. 351-352, 1936. 
^ Op. cit 


grades eastward into the upper Sacate ("Coldwater") sandstone from 
which it is not differentiated. 

Alegria Formation 

The Alegria formation is the marine facias of the continental Sespe 
formation in Gaviota and Point Conception ((nadrano-les. The Alegria 
consists of about 1200 feet of sandstone and a minor amount of siltstone 
lying conformably above the Gaviota formation and disconformably 
below the Vaqueros formation. 

The Alegria formation, generally known as "marine Sespe," is 
developed only on the south flank of the Santa Ynez Range between a 
point 4 miles north of Point Conception and Capitan Canyon. The type 
locality is designated as the ridge east of Canada de Santa Anita, where 
the section is as follows : 

Vaqueros sandstone and conglomerate. 


G Buff, laminated friable fine- to medium-grained sandstone 250' 

F Poorly exposed soft greenish siltstone. Thickens eastward, lenses 

out westward 10' 

E Gray-white to buff, friable medium- to fine-grained sandstone. 

Becomes pebbly eastward 110' 

D Soft light gray-brown poorly to well-bedded siltstone and thin 

layers of very fine sand 150' 

C Light-buff friable massive to thick-bedded medium-grained sand- 
stone ; lower 90 feet gray, coarse grained, and contains several 
oyster reefs 2.30' 

B Soft greenish-brown silty to sandy clay shale 80' 

A Light-buff to gray friable massive sandstone with few small 

rounded pebbles 180' 

Total 1010' 
Gaviota siltstone 

These members vary along the strike in lithology and thickness, but 
the above type of lithology is characteristic of the Alegria formation 
throughout its extent. It is made up predominantly of medium- to coarse- 
grained, thick-bedded sandstones which form prominent exposures. They 
are generally fossiliferous and are shallow-marine littoral deposits. In 
the most westerlj^ exposure siltstone members B and D become somewhat 
brown and organic and weather pale gray. Eastward from Alegria 
Canyon member G thickens to more than 600 feet. From Agua Caliente 
Canyon the Alegria formation grades laterally eastward into the non- 
marine Sespe formation, with the first red clays appearing in member G 
at Gaviota Canyon, but green clays of possible nonmarine origin persist 
in this member as far west as Cuarta Canyon. Eastward from Gaviota 
Canyon, red clays appear progressively lower in the section, until at 
Capitan Canyon they occur throughout the section, which apparently is 
all nonmarine. The standstones retain their buff color even where they 
become unfossiliferous and supposedly nonmarine, so that it is difficult 
to determine just where the Alegria formation grades into Sespe. 
Bailey ^^ extends the Sespe nonmarine beds as far west as Santa Anita 
Canyon. The contact between the predominantly marine Alegria forma- 
tion and the predominantly nonmarine Sespe is shown approximately 
on the geologic map. 

SI Bailey, T. L., Origin and migration of oil into Sespe red beds, California : Am. 
Assoc. Petroleum Geologists Bull., vol. 31, no. 11, pp. 1913-1935, 1947. 


The Alegria formation lies conformably upon the upper siltstone 
member of the Gaviota formation. Eastward from Arroyo Hondo, where 
the upper Gaviota becomes sandstone, the two formations are difficult to 
differentiate. The relationship of the Alegria to the overlying Vaqneros is 
an unconformity, as indicated by gradual overlap of successive beds of 
the former from east to west ; west of Cojo Canyon there is an angular 
discordance of about 15°. 

At Bulito Canyon the top of member C of the Alegria carries the 
following molluscan species : 

Ostrea tayloriana Gabb 

Pecten (Chlamys) yueziana Arnold 

Tivela inezana Conrad 

Turritella variata Conrad 

This fauna is the same as that of the underlying Gaviota formation, 

and thus places the Alegria in the Refugian stage of the Oligocene. 

Kleinpell "- reports a Zemorrian microfauna from green siltstone west of 

Gaviota Canyon, which is believed to be member F of the Alegria 


Sespe Formation 

The Sespe formation in the western Santa Ynez Mountains is a 
series of continental sandstones, clays, and conglomerate lying above the 
Gaviota or older formations and below the Vaqneros sandstone. 

The Sespe formation is best developed on the south slope of the 
Santa Ynez Range in the vicinity of Capitan and Corral Canyons. Here 
it consists of about 2200 feet of pinkish-gray to buff friable laminated 
sandstone interbedded with red and green clays and silts. Westward 
along the strike the prevailing pink color of the sandstones gives way to 
gray and buff. Only the fine sediments retain their red color. The thick 
basal conglomerate of the Sespe in the Santa Barbara-Goleta area is not 
present in the area mapped. Between Refugio and Gaviota Canyons 
progressively lower beds of the Sespe formation grade laterally west- 
ward into the marine Alegria formation. 

In the Santa Rosa Hills and eastward to Quiota Canyon the Sespe 
formation averages about 500 feet in thickness and consists of coarse 
basal green conglomerate composed almost entirely of Franciscan debris, 
grading upward into red and green friable sandstone and interbedded 
variegated clays and silts. Here the Sespe lies on Gaviota or older forma- 
tions with a great regional unconformity, but grades upward into 
Vaqneros marine beds. In this area the Sespe is of Zemorrian age (lower 
Miocene) as it unconformably overlies the Gaviota formation of Refugian 
age, and in part grades into marine Vaqneros in the western Santa Rosa 
Hills. On San Julian ranch, however, the Sespe is overlapped on the 
northwest by the marine Vaqneros conglomerate. 

Vaqueros Formation 

The Vaqueros formation in the western Santa Ynez Mountains con- 
sists of as much as 600 feet of marine sandstone and conglomerate of 
Zemorrian age (lower Miocene) lying above the Sespe, Alegria, or older 
formations and conformably below the Rincon shale. 

On the south slope of the range the Vaqueros sandstone forms a very 
prominent and continuous brush-covered ledge from Bixby Canyon, 

^ Schenck and Kleinpell, op. cit. 


north of Government Point, for some 27 miles eastward across Point 
Conception and Gaviota quadrangles. Between Canada del Capitan and 
Arroyo Hondo the Vaqneros consists of about 200 feet of light-graj^, 
friable to hard calcareous, cross-bedded medium- to coarse-grained sand- 
stone. Westward the lower portion becomes pebble conglomerate. At 
Gaviota Canyon the Vaqueros thins down to 25 feet, but thickens again 
toward the west and averages about 75 feet west of Alegria Canyon. 

The Vaqueros formation is best developed on the north flank of the 
Santa Ynez Mountains in the vicinity of Nojoqui and Alisal Canyons. 
Here it is about 600 feet in maximum thickness and consists of light 
greenish brown concretionary fine- to medium-grained sandstones inter- 
bedded with massive gray siltstones. In this area the Vaqueros grades 
downward into the underlying Sespe and upward into the Rincon shale. 

In San Julian Valley and westward to the Tranquillon Mountain 
area, the Vaqueros consists of as much as 300 feet of buff sandstone grad- 
ing doAvnward into greenish-brown fossiliferous, cross-bedded basal con- 
glomerate composed almost entirely of Franciscan debris. 

On the south slope of the Santa Ynez Range, eastward from Gaviota 
Canyon, the Vaqueros sandstone lies with a sharp, possibly disconform- 
able, contact on the Sespe, but no conclusive evidence of an unconformity 
is indicated here. Farther west, the Vaqueros gradually overlaps the 
upper members of the Alegria, and west of Co jo Canyon this becomes 
an angular unconformity. A great regional unconformity becomes 
strongly developed throughout the northwestern part of the Santa Ynez 
Mountains, where the Vaqueros overlaps the eroded edges of the Gaviota 
and older formations which had previousl}^ been compressed into broad 
folds trending slightly north of west. A nearly similar condition holds 
true for the unconformity at the base of the Zemorrian Sespe in the 
Nojoqui- Alisal area, which was probably developed at the same time or 
slightly earlier. 

The Vaqueros formation contains the following molluscan species 
in the western Santa Ynez Mountains : 


Ostrea eldridgei Arnold (large) 
Pecten (Pecteu) vanvlecki Arnold 
Pecten (Lyropecten) magnolia Conrad 
Pecten ( Chlamys ) sespeensis Arnold 
Traehycardium vaquerosensis Arnold 
Macoma nasuta (Conrad) 


Turritella inezana Conrad 
Turritella inezana var. altacorona 
Rapana vaquerosensis (Arnold) 

Pecten (Lyropecten) magnolia and Turritella inezana are abundant 
in the basal conglomerate throughout the northwestern Santa Ynez 
Mountains. The other species occur more abundantly in the Vagueros 

The above fauna places the Vaqueros formation of the Santa Ynez 
Mountains in the Zemorrian stage, lower Miocene. 




i^chenck. lii',1. 



Tvpe exposure of Jalanm formation showing fossiliferous .f ""intones at left of 

camonrSpper shale member and sandstone at right. Photo Inj H. G. Schencl, IS)!. 






Matilija sandstone beds at right, oveiiain by Cozy Dell shale at middle, in turn 
overlain bv Sacate sandstone, which forms peak at left of picture. Photo by 

H. G. Schcnck, 19.',1. 



Skyline ridge formed by Gaviota sandstone. 



Beds dip southwest ; 3.3 miles south of Buellton, 0.3 mile west of Nojoqui Creek. 


Light-colored beds on high bluffs are Vaqueros sandstone, underlain by "Sespe" 
conglomerate and Cozy Dell shale, which form grassy slopes. Lower brush-covered 

hills are Jalama? formation. 




•1 •'..«**<" 


.' 'ffi^» 

.V . 


*» , 

.•\ V 



v OsJ 




0.7 mile north of Jalama Creek, 4.6 miles of mouth. Conglomerate contains 

abundant Pecten magnolia and Turritella inesana. Bed dips 85° N. (to right). 

In Member B, lower Monterey shale, east of Alegria Canyon. 


Rincon Claystone 

The Rincon ela.ystone is about 1500 feet thick and lies conformably 
above the Vaqneros sandstone in the Santa Ynez Mountains. 

On the south flank of the range the Rincon forms a continuous 
exposure adjacent on the south to the Vaqneros sandstone across Point 
Conception and Gaviota quadrangles. It is also well exposed through 
Quiota, Alisal, and Nojocjui Canyons, in the Santa Rosa Hills, San 
Julian and Jalama Canyons, and in the Tranquillon Mountain area. 
The Rincon lies conformably on the Vaqneros everyw'here except on 
Tranquillon Mountain ridge, -where it lies unconformably on the Espada 
formation, the Vaqneros having buttressed out. The relationship with the 
overlying Monterey is conformable except in the northwestern Santa 
Ynez Mountains, where it is unconformable. 

The Rincon formation at all exposures is made up of brown-gray 
poorly bedded to massive clay shale with spheroidal fracture ; yellow- 
weathering calcareous concretions are common. In the more northerly 
exposures in San Julian Valley and at Tranquillon Ridge the Rincon 
claystone is somewhat hard and weathers nearly white, probably because 
of its siliceous or bentonitic material content. The Rincon readily weath- 
ers into a clayey adobe soil which forms low grass-covered slopes, in 
marked contrast to the brush-covered Vaqneros sandstone outcrops. 

The lower third of the Rincon claystone carries an upper Zemorrian 
(lower Miocene) foraminiferal fauna. The upper two-thirds of the Rin- 
con carries a Saucesian (upper lower Miocene) foraminiferal fauna. 

Lospe Formation 

The Vaqueros-Rincon formations are not known to occur in the 
Santa Maria Basin, but may be represented by the lower Miocene (?) 
Lospe formation, consisting of 2700 feet of terrestrial reddish and green- 
ish sediments and lenses of white indurated tuff, exposed in the Casmalia 
Hills. This section starts with a basal conglomerate of debris derived 
from the underlying Franciscan, and grades upward through bedded 
sandstones into gypsiferous mudstone which is overlain b}" the Relizian 
Point Sal formation. 

The Lospe formation underlies Casmalia and Orcutt oil fields, and 
may underlie Burton j\Iesa and Lompoc oil field ; for several wells pene- 
trated a thin series of gray and reddish sandstones and tuff'aceous ( '?) 
rocks betAveen the Monterey shale and Franciscan, which may be either 
the Lospe formation or the equivalent of the Tranquillon volcanics or 
Obispo tuff. 

Tranquillon Volcanics 

The Tranquillon volcanics are a local phase of the Obispo tuff of 
San Luis Obispo County, and are composed of as much as 1200 feet of 
rhj'olite, agglomerate, and ash exposed on Tranquillon Mountain ridge 
and vicinity. Here this volcanic series lies conformably below the ]\Ion- 
terey shale and unconformably above Rincon and older formations. It 
is generally regarded as the basal member of the Monterey formation, 
but since it is a rock unit distinct from any other in this area, it is treated 
as a formation. The type locality is designated as the ridge west of 
Caiiada del Rodeo. 

The Tranquillon volcanics are made up mainly of a large rhyolite 
flow which forms Tranquillon Peak and the large dip-slope on the south 

3 — 13966 


side of this same ridge. The rhyolite is buff colored, dense to slightly 
porphyritic, and shows prominent fiow-structure. The flow lenses out 
east and west of the ridge, and is replaced by rhyolite agglomerate and 
tuff at Point Pedernales and in the vicinity of Jolloru Canyon. The 
rhyolite may have erupted along the ridge immediately north of Tran- 
quillon Peak or from the exposure north of Canada Honda Creek, but 
its source is not definitely known. 

East of Jolloru Creek the Tranquillon volcanics lens out, but reap- 
pear locally in other parts of the western Santa Ynez Mountains. At 
Bixby Canyon 3 miles north of Government Point they appear as a lens 
up to 50 feet thick of rhyolite tuff-breccia at the base of the Monterey 
shale. Farther east they are represented by local occurrences of bentonite 
at this horizon. 

Other exposures of Tranquillon volcanics occur along the Santa 
Ynez River in the vicinity of the Santa Rita Hills, comprising basalt, 
basaltic agglomerate, tuff, and bentonite totaling 500 feet in maximum 
thickness. About 690 feet of basalt was drilled through in Tidewater 
Associated Oil Co. No. "Leonis" 1 well. 

On the south side of the Santa Ynez River south of Solvang is a 
quarry in which about 75 feet of Tranquillon formation, composed of 
sandstone, hard indurated tuff, and algal limestone, is exposed. 

At Quiota Canyon the Tranquillon formation is represented by 
about 30 feet of pumice tuff and bentonite on the hill southwest of the 
canyon. On the east side of this canyon is about 60 feet of medium-grained 
buff sandstone with a 5-foot layer of bentonite and pumice tuff near the 

In El Jaro Canyon below the juncture with Amoles Creek is a layer 
of limestone about 50 feet thick, at the base of the Monterey shale. The 
basal portion contains tuff, sandstone, and conglomerate which may be 
equivalent to the Tranquillon volcanics. 

The Tranquillon formation is upper Saucesian in age (upper lower 

Miocene). This is indicated by the presence of upper Saucesian fora- 

minifera at Capitan Beach, in the upper Rincon shale underlying the 

Tranquillon bentonite bed, and also in the overlying basal Monterey 

shale. On the basis of microfauna the Tranquillon volcanics definitely 

correlate with the Obispo tuff at the mouth of Cuyama River. On the 

east side of Quiota Canyon the sandstone of the Tranquillon formation 

carries the following molluscs : 

Pecten (Amusium) lompocensis Arnold 
Pecten (Lyropecten) estrellanus (Conrad) 
Pecten (Lyropecten) magnolia Conrad 
Turritella ocoyana Conrad 
Turritella temblorensis Wiedey 

Monterey Shale 

The term Monterey shale, as used in this report, includes all the sedi- 
ments lying above the Rincon shale (and above the Tranquillon volcanics 
where present), and below the Sisquoc formation. The Monterey shale 
as herein used is the same as the Modelo formation of the Ventura Basin. 
The Monterey shale is made up of predominantly siliceous shales ranging 
in age from uppermost Saucesian to lower Delmontian of the Miocene. 
The Monterey shale herein includes the Relizian Point Sal formation of 
the northern Santa Maria Basin as mapped by Woodring and others,^^ 

«» Op. cit, 1944. 


as this unit loses its identity as a formation and becomes inseparable from 
the Monterey shale in the Santa Ynez Mountains and southern Santa 
Maria Basin. 

Throughout the area mapped the Monterey shale is divisible into two 
lithologie members, lower and upper. The lower Monterey is characterized 
by a mixture of clayey shales, siliceous shales, and limestones, and the 
upper Monterey by siliceous shales. The upper ]\Ionterey as used in this 
report corresponds to the "Middle and Upper member" of the Monterey 
as mapped ^^ in the northern Santa Maria Basin, and the lower Monterey 
to the "Lower member" of the Monterey and the Point Sal formation. 

In the Santa Ynez Mountains the Monterey shale averages about 
1700 feet in thickness, and both members are well exposed. In the portion 
of the Santa ]\Iaria Basin mapped the Monterey shale is present nearly 
throughout, but is buried by later formations except in Burton Mesa and 
eastern Purisima Hills, where the upper member crops out. The Monterey 
shale ranges from 1800 to 4500 feet in thickness in the Santa Maria Basin. 

Santa Ynez Mountains. The Monterey shale is well exposed in the 
Santa Ynez ]\Iountains where it ranges from 1200 to 2000 feet in thickness. 
On the south flank of the range, and in the Santa Rosa Hills, the Monterey 
lies conformably on the Rincon. However, elsewhere in the Santa Ynez 
Mountains, especially throughout the northwestern portion, the Monterey 
shale, or the Tranquillon volcanics where present, lie unconformably on 
the eroded surface of older formations ranging from Rincon to Fran- 
ciscan. The relationship of the Monterey to the overlying Sisquoc is 
conformable except for a local disconf ormity developed in the Santa Rita 
Hills and on the coast west of Gaviota. 

The Monterey shale is well exposed on the south flank of the Santa 
Ynez Range west of Gaviota. Here the section is divisible into five litho- 
logic members, each with a distinct microfauna. 

The sequence shown in the section (page 36) holds true for most of 
the Santa Ynez ■Mountains, but because of structural complexity and 
poor exposures the various members cannot everywhere be mapped. 

In the Santa Ynez IMountains the lower Monterey shale averages 
about 800 feet in thickness, and attains its maximum of 1800 feet at San 
Pascual Canyon. It locally buttresses out against older formations in 
Salsipuedes Canyon, and also at San Lucas Canyon. The lower Monterey 
consists of a heterogeneous series of well-bedded shales of various t5T)es, 
composed of soft phosphatie shales, fissile organic shales, impure diato- 
mite and siliceous shales, and interbedded limestone beds. Thin layers of 
volcanic ash are common. Layers of clay shale and siltstone are common 
in the lower (Relizian) portion. From Cailada de la Vina westward the 
lower Mohnian portion grades laterally into cherty shale which is mapped 
with the upper ]\Ionterey. In the vicinity of Tranquillon Mountain the 
entire lower ]\Ionterey shale is largely composed of cherty shale which is 
difficult to separate from the upper Monterey. 

The lower Monterey is weakly resistant to erosion but more resistant 
than the underlying Rincon. It tends to form landslides. The lower Mon- 
terey weathers to a deep heavy adobe soil which supports only grasses 
and annual herbs. 

Throughout most of the Santa Ynez Mountains the upper Monterey 
shale averages about 950 feet, but it thickens to more than 3000 feet at 

** Woodring, W. P.. and others, op. cit., 1944. 



[Bull. 150 

Monterey shale section exposed on south flank of S!anta Ynez Range 
hetireen Cojo and (lariola Canijons. 

Sisquoc shale with basal sand and chert conglomerate east of Sacate Canyon. 


F Hard laminated brown platy porcelaneous shale which 
weathers wliite. Carries lenses of chert conglomerate 
east of Cuarta Canyon. Ahnndant diatoms, sparse fo- 
raminifera. Delmontian stage, upper INIiocene 100'-200' 

Upper Monterey 

E Hard laminated brittle opaline cherty .shales grading 
into above member. Contains layers of dark chalcedonic 
chert westward from Gato Canyon. Sparse foraminif- 
era. Upper Mohnian stage, upper Miocene 2r)0'-.550' 

Lower Monterey 

Rincon clay shale 

I) Soft, laminated fissile diatomaceous .shales; phosphatic 
shales ; occasional thin limestones ; minor porcelaneous 
and cherty shales. Abundant foraminifera. Lower 
Mohnian stage, upper Miocene IHO'-.SOO' 

C Hard white limestone and interbedded thin strata of 
soft diatomaceous shale, minor amounts of phosphatic 
shale, and laminated siliceous shale. Abundant foram- 
inifera, especially Valvulineria, califoniica and Sipho- 

generinu coUonii. Luisian stage, middle Miocene 


B Soft ))uiif-weathering bedded to massive siltstone, silty 
siliceous shale, and buff-weathering limestone beds. 
Foraminifera abundant locally. Relizian and upper- 
most S.uicesian stages, middle ^Miocene 160'-4B0' 

A Bentonite, equivalent to Tranquillon volcanics O'-IO' 

Aggregate thickness 1010'-1440' 


San Lucas Canyon. On the south flank eastward from Gato Canyon and 
on the north flank eastward from Solvang the upper Monterey is char- 
acterized by hard, browu. platy porcelaueous shale. On both flanks of the 
range this grades westward into opaline clierty shales, which in the 
extreme western Santa Ynez Range contain numerous layers of heavy 
contorted chalcedonic chert. 

Phases of pure punky laminated diatomite are locally interbedded 
in the cherty shale of the upper Monterey at Salsipuedes. San Miguelito, 
and Jalama Canyons. Most of these occur toward the top. but at Salsi- 
puedes Canyon some occur far down the section. The 1000 feet of pure 
laminated diatomite overlying the Monterey siliceous shales at the 
Lompoc quarries and vicinity has been mapped as the lower Sisquoc for- 
mation. It is of Delmoutian (upper Miocene) age. At the beach west of 
Ga^dota Canyon are several lenses as much as 75 feet thick of well-bedded 
conglomerate in member F of the ]\Ionterey and at the base of the Sisquoc. 
This conglomerate is made up of unsorted angular to sub-rounded cob- 
bles and pebbles composed mainly of ]\Ionterey cherty shale ; there are 
also some pebbles of quartzite. porphyries, sandstone, etc. The matrix is 
a tar-soaked cross-bedded sand made up largely of quartz grains. The 
occurrence is remarkable, as at this locality the Monterey is made up of 
porcelaueous shale, and no clierty shale is present. The conglomerate is 
apparently the result of some local uplift and erosion at the end of depo- 
sition of the upper Monterey shale. 

The upper Monterey siliceous shale is rather strongly resistant to 
erosion. Since the shales are hard but closely fractured they form high 
but rounded hills and narrow, steep-sided canyons. They develop little 
soil and generally support brush or oak timber, in contrast to the lower 
Monterey which forms open gras.slands. 

Santa Maria Basin. The Monterey shale underlies nearly all of the 
Santa Maria Basin mapped, but is generally concealed by younger forma- 
tions. Only in Burton ]\Iesa and eastern Purisima Hills the upper Mon- 
terey is exposed. However, data on the distribution and thickness of the 
Monterey shale where concealed have been furnished from well-logs. 

On Burton ]\Iesa and the south flank of the Purisima Hills the ]Mon- 
terey shale averages slightly less than 2000 feet, but thickens northward 
to some -toOO feet on the north flank of the Purisima Hills and perhaps 
under Los Alamos Valley and upper Santa Ynez Valley. Throughout 
most of the Burton Mesa, Lompoc Valley, and Purisima Hills the Mon- 
terey is luiderlain by Franciscan or Espada formations, except for some 
local intei'^-eniug tuffaceous sediments thought to be the Lospe formation. 
This condition indicates a great regional unconformity at the base of the 
Monterey shale. The Monterey is conformably overlain by the Sisquoc 
diatomite in the Santa ]\Iaria Ba.sin. except under the San Rafael foot- 
hills, where it is successively truncated northeastward by the Sisquoc. In 
the northeastern portion it is completely overlapped. 

Both members of the Monterey shale are present in the Santa ]\Iaria 
Basin and their lithologic character is the same as in the Santa Ynez 
Mountains. The exposures of upper Monterey in Burton Mesa and east- 
ern Purisima Hills consist of close-fract>ired cherty shale grading 
upward into porcelaueous platy shale. 








Silts ond gravels 


G ravel s 

E 3200+ 

Diatomaceous siltstone. 

Clay shale or 
diatomaceous mudstone. 

Thin-bedded clay shale or 
laminatffd diatomite. 


Porcela neous arid cherty 
Siliceous shales. 

Organic shales and 
thin limestones. 


Rhyolite and basalt lava, 
agalomerate, tuff, bentonite. 

; 0-1700 

CI ay stone. 

r 0-900' 

Sandstone i conglonnerate. 

Pink to buff sandstone and 
red and green siltstone. 

Gray to buff marine 

Fossiliferous buff 
sandstone and siltstone. 

Buff sandstone and 
clay shale. 

Brown clau ehale. 

Buff arkosic sandstone. 

Dork gray cloy shale. 

Algol llmettone lent. 

Buff finegrained sandstone. 
Groy siltstone. 

Buff sandstones and 
gray clay shales. 


Jurassic Upper 

Dark greenish brown 
carbonaceous shales and 
thin sandstones. 

Basal pebblij sandstone. 

Dark greenish brown 
nodular claystone. 

Hard green sandstone and 
black shale. 
Serpentine intrusions. 

Figure 2. Stratigraphic column, western Santa Ynez Mountains. 








Dune Sond 


Wind blown sand 



Silt, sond. grovel 


Te r r a ces 


Gravel, iond. 



Sond, bosol grovel. 



Paso Robles 


Cobble and boulder grovel. 

Shale-pebble grovel, silt. 

Pebbly gray silt, clay, sand. 
Basal marl. 



Pliocene , 

— ? — 


Fox en 

Buff sand, pebbly sand. 
Fine yellow sond. 


Gray cloystone 




M iocene 


Diotomite and clQustone. 

Diatomaceous claystone 

Lominoted diotomite ond 
diatomaceous shale. 



Lospe ? 

Porcelaneojs siliceous ihote 

Chertti Siliceous shale. 

Organic shales ond 
thin limestones. 


Reddiih sandstone, tuff 

Cretaceous Lower 

Espada or 

Jurassic Upper 


Dark greenish brown 
cloy shale and sandstone. 

Ill III I" ii> III 

Hord green sandstone. 

Sheared black clay stone. 

Varicolored cherts. 

Massive to amyqdaloidal 


Numerous serpentine 


Figure 3. Stratigraphic column, southern Santa Maria Basin. 


Lithologic Character. The Monterey shale differs from all other 
formations in the mapped area and is remarkable for the following 
reasons : ( 1 ) widespread areal extent ; ( 2 ) low percentage of clastic sedi- 
ment; (3) presence of volcanic material; (4) high percentage of chemi- 
cal sediments ; (5) very high percentage of siliceons sediments ; (6) large 
amount of organic material; (7) rhythmic bedding. 

The Monterey shale, and perhaps the overlying Sisquoc, are the only 
Tertiary formations deposited over the entire mapped area. The local 
absence of Monterey shale under the northeastern San Rafael foothills 
and in parts of the Santa Ynez Mountains is due to its removal by uplift 
and erosion after deposition. The Monterey formation contains no mar- 
ginal type sediments and there is no evidence that it was not deposited 
over the entire mapped area. Local absence of the lower Monterey, how- 
ever, may be due to non-deposition. 

The Monterey shale is the only formation in the mapped area con- 
taining almost no clastic material. Only the lowest (Relizian) portion 
contains an appreciable amount of silt and clay. This material decreases 
upward to almost none in the uppermost Monterey. Sand and con- 
glomerate are absent except for the local occurrence of chert pebble 
conglomerate and sand west of Gaviota Beach. The general absence of 
clastic material in the Monterey formation is apparently due to wide- 
spread submergence under an open sea and disappearance of the adjacent 
land areas which furnished clastic materials to older formations. 

The occurrence of the Tranquillon volcanics and Obispo tuff at the 
base of the Monterey strongly suggests that volcanism had strong influ- 
ence on the deposition of the siliceous sediments that make up most of the 
Monterey. Thin layers of volcanic ash and some bentonite are common 
throughout the Monterey shale. The Tranquillon rhyolitic eruptions may 
have been a source of some of the enormous quantities of silica in the 
Monterey shale, either by means of alterations of volcanic ash in the sea 
water, or from submarine siliceous springs which may have issued 
throughout Monterey time from the former areas of volcanic eruptions. ^^ 
There is no physical evidence to support these theories, except that the 
upper Monterey generally becomes more cherty and siliceous in the 
vicinity of Tranquillon Mountain. This is generally true of the lower 
Monterey also, which consists predominantly of cherty shale in that 
vicinity. Aside from the Franciscan, the Tranquillon is the only volcanic 
series within the mapped area and the Monterey the only formation 
containing appreciable amounts of volcanic ash. 

The Monterey shale is believed to be essentially a chemical deposit, 
made up predominantly of silica. Although much of this was deposited 
organically in the form of diatom tests, the silica itself must have had a 
chemical origin, and that not used by organisms must have settled out 
from colloidal suspension and deposited in much the same manner as 
calcium carbonate does to form limestone. The lower Monterey contains 
an appreciable amount of limestone as beds averaging about a foot in 
thickness. A thick basal limestone as much as 150 feet thick forms the 
base of the Monterey in the canyon of El Jaro Creek. Although some of 
the calcium carbonate making up the limestone was deposited orginally 
by foraminifera and calcareous algae, most of it is of chemical origin. 

^ Taliaferro, N. L., The relation of volcanism to diatomaceous and associated 
siliceous sediments: Univ. California Dept. Geol. Sci. Bull., vol. 23, no. 1, pp. 1-56, 1933. 


I'LATK 14 



Member F, upper Monterey, near mouth of 

Alegria Canyon. 

4 — 13966 






Member D, lower Monterey shale, in Alegria Canyon. 

Member E, upper Monterey shale, near mouth of Jalama Canyon. 



". iJ » •->• -4^ 


Sisquoc shale exposed along beach : Monterey shale forms hills hack of coastal 

terrace. Derrick of Wilshire Oil Companj- well No. ■Hollister" 1 on sea cliff. 

^ -^i^^jj^ 



7 miles east of Santa Ynez. Made up largely of shale pebbles. 




.'it- *"''3' ,'7 , *' i 




Near top of Monterey shale, east of Alegria 
Canyon half a mile from beach. 


Calcium phosphate was deposited in the form of eollophane which 
makes up the buff-colored blebs and lenticular laminae in soft, dark 
brown organic shales. This type of shale, kno^vn as phosphatic or "buff 
and brown" shale in oil fields, is characteristic of the lower Mohnian and 
Luisian portion of the lower Monterey. 

The Monterey shale is remarkable for its enormous quantities of 
silica. The siliceous rocks of the Monterey and part of the overlying 
Sisquoe formation are of three types, as recognized by Bramlette,^® all 
of which are finely laminated and grade into one another : (1) diatomite 
(soft, white, "punky," lightweight, porous); (2) porcelaneous shale 
(hard, brown, white-weathering shale with platy fracture) ; (3) cherty 
shale (very hard, brittle, vitreous, black, bro^vn, gray, to white opaline 
shale with close sub-platy to conchoidal fracture ; contains laminae or thin 
layers of black to brown chalcedonic chert [flint] ; commonly minutely 
contorted, brecciated and recemented by veinlets of secondary opal or 

Porcelaneous and cherty shale are characteristic of the upper Mon- 
terey, and occur locally in the lower ^Monterey. The diatomite is 
characterictic of the lower Sisquoe formation in some areas, but is also 
locally interbedded in the siliceous shales of the upper Monterey. 

Considering the areal extent of the Monterey shale in California, 
it is difficult to postulate where such a great amount of silica could have 
originated. Many theories have been proposed, and these are thoroughh^ 
discussed by Taliaferro ^^ and Bramlette.^^ The inorganic theory as 
advanced bv Taliaferro "^ has alreadv been discussed. The organic theory- 
postulates that the hard siliceous shales were formed by alteration of 
organically deposited diatomite by deformation,^" or by compaction from 
overljing sediments.^^ However, neither the source of the siliceous sedi- 
ments nor the process by which they were formed can be accounted for 
satisfactorily by these theories, and there is little direct evidence to 
support them. How the enormous quantity of silica was made available, 
or exactly how it was deposited to form siliceous shales, is not known. 

The normal sequence of the three types of siliceous sediments is the 
order given, cherty shale making up the lower part of the upper Mon- 
terey', and grading upward through porcelaneous shale into diatomite. 
]\Iuch of the contact between the siliceous shale and diatomite is sharp 
and easily mappable. Detailed mapping shows that the three t^-pes are 
not at the same position in the section at all places ; in some localities they 
are interbedded. From these relationships it is concluded that these three 
tyipes of siliceous sediments are of primary origin and that they are f acies, 
as suggested by Regan and Hughes,^^ determined b}^ local conditions of 
deposition, the relative amount of free .silica deposited, and the amount 
deposited by organisms. 

38 Bramlette, M. N., Monterey formation of California and origin of its siliceous 
rocks : U. S. Geol. Survey Prof. Paper 212, pp. 1-55, 1946. 

^" Taliaferro, N. L.., The relation of volcanism to diatomaceous and associated 
siliceous sediments: Univ. California Dept. Geol. Sci. Bull., vol. 23, no. 1, pp. 1-56, 1933. 

»8 Op. cit. 

»9 Op. cit. 

*° Arnold, R., and Anderson, R., op. cit. 

" Bramlette, M. N., op. cit. 

<^ Regan, L. J. Jr., and Hughes, A. "W., Fractured reservoirs of the Santa Maria 
district, California : Am. Assoc. Petroleum Geologists Bull., vol. 33, no. 1, pp. 32-51, 1949. 



The Monterey shale is notable for its unusually large amount of 
organic debris, composed largely of remains of microscopic plant and 
animal life. The highly siliceous content of the marine waters following 
eruption of the Tranquillon volcanics apparently brought about a con- 
dition favoring unusually prolific development of one-celled plants such 
as diatoms. These were produced in such enormous quantities, especially 
during late Monterey deposition, that their siliceous tests accumulated to 
form thick deposits of impure to nearly pure diatomite, making up a 
large percentage of the siliceous shales of the Montere.y. Along with the 
diatom debris but in lesser amounts were deposited siliceous remains of 
animals, such as tests of radiolaria and arenaceous foraminifera, and 
sponge spicules. Calcareous tests of foraminifera are extremely prolific 
only in the lower ]\Ionterey, and tests of arenaceous foraminifera are 
abundant in both members. The former are extremely abundant in some 
layers, especially in the phosphatic shales and thin limestone beds. 
Chitinous remains of fish scales are abundant throughout the Monterey. 
Molluscs are rare except for mud-pectens {'' Pccten" pecJxhami) and 
other small thin-shelled pelecypods. 

Besides the remains of organic life the Monterey shale contains a 
great amount of organic matter in the form of hydrocarbons or bitu- 
minous material. Where unweathered the Monterey shale is generally 
impregnated with this material, which gives the characteristic bitumi- 
nous odor when freshly broken and imparts a dark brown color to the 
sediments. Where exposed, this organic matter leaches or oxidizes so 
that the rocks become light colored or even white. It is most abundant 
in the upper Monterey, which produces practically all the oil at Lompoc 
and Zaca oil fields. This organic matter was probably deposited in water 
too deep and too far below wave and current action to be subject to 
oxidation, and consequently became buried and preserved in the fine 
sediments of the Monterey. 

A characteristic feature of the Monterey shale is the rhythmic bed- 
ding, which is described in detail by Bramlette.'^^ This feature is most 
apparent in the siliceous shales, in which the rhythmic beds are 1 inch or 2 
inches thick and consist of hard porcelaneous or cherty shale alternating 
with layers of softer somewhat more clayey shale. Superimposed on this 
rhythmic sequence of beds is a series of fine laminae which likewise shows 
a definite alternation of layers that contain abundant siliceous or organic 
matter with those that contain less. These rhythmic laminae are believed 
to represent annual cycles of deposition. 

Age. The lower Monterey and upper Monterey are mapped as 
lithologic units and the contact separating them is not necessarily a time 
horizon. The ages of the various sub-members west of Gaviota are already 
indicated. In the Santa Ynez Mountains the upper Monterey falls into 
the lower Delmontian stage and upper Mohnian stage {Bolivina kughesi 
zone), upper Miocene, and locally includes some lower Mohnian. The 
lower Monterey falls into lower Mohnian {Baggina calif or nica zone) ; 
Luisian stage (Siphogenei'ina collomi-ValvuIineria californica zone) ; 
Kelizian stage (SipJiogenerina hranneri zone), middle Miocene; and 
uppermost Saucesian stage {Uvigerina ohesa zone), uppermost lower 

*3 0p. cit, pp. 30-34. 


Sisquoc Formation 

The Sisquoc formation in southwestern Santa Barbara County con- 
sists of from 3000 to 5000 feet of diatomite and diatomaceous clay shale 
lying" above the JMonterey shale and below the Foxen and Careaga for- 
mations. The Sisquoc formation is exposed on both flanks of the Santa 
Ynez Range, on Burton Mesa, and throughout the Purisima Hills. The 
type locality is on the south side of Sisquoc River canyon near the mouth 
of Foxen Canyon, north of the area mapped, where the Sisquoc consists 
predominantly of fine sands. 

The Sisquoc formation is best developed in the Purisima Hills, where 
it attains a thickness of nearly 5000 feet. The general sequence here is 
as follows : 

Foxen claystone 

Gray-white poorly bedded diatomaceous claystone, with a pre- 
dominant 200-foot layer of laminated white diatomite 

("marker diatomite") at middle 1000± feet 

Variations from light-gray massive to poorly bedded diato- 
maceous claystone with couchoidal, spheroidal, or splintery 
fracture, to cream-white well-bedded to massive impure 
diatomite ; north of Lompoc field lowest exposed portion 
contains layers up to 6 inches of massive brown opaline 
chert ; in eastern Purisima Hills lowest portion becomes 

massive to laminated white diatomite 4000± feet 

Massive, semi-friable fine-grained brown sand, impregnated 

Avith tar 0-50 feet 


Monterey — laminated diatomite and platy siliceous shale 

In the Burton Mesa area the Sisquoc formation is about 2300 feet 
thick and is similar in lithology to the Sisquoc of the Purisima Hills. The 
upper 300 feet is composed of nearly pure laminated white diatomite 
which is probably the equivalent of the marker diatomite of the Purisima 
Hills. The remaining 2000 feet consists of diatomaceous claystone with 
splintery fracture, of which the low^est 700 feet becomes thin-bedded 
diatomaceous porcelaneous shale which grades downward into Monterey 
platy shale. 

In the Santa Rita Hills and west along the hills south of Lompoc 
Valley the lowest 750 to 1000 feet of Sisquoc consists of soft, white, lam- 
inated, punky, almost pure diatomite. This is quarried extensively south 
of Lompoc. It generally g-rades downward into cherty shale of the under- 
lying Monterey, but at several localities near the Santa Ynez River 
between Salsipuedes and Drum Creeks the base of the diatomite is 
marked by a few feet of sand locally, or by a thin layer of phosphatic 
pebbles, which can best be seen in a road cut near the mouth of Drum 
Canyon and on the Santa Rosa road east of Salsipuedes Creek. In the 
eastern Santa Rita Hills the Sisquoc diatomite overlaps the entire upper 
Monterey, thus indicating a local unconformity. The punky diatomite 
member "of the Sisquoc grades upw^ard into 750 to 1050 feet of massive 
cream-white diatomaceous claystone. This is unconformably overlain by 
the Careaga sand. 

On the south flank of the Santa Ynez Range the Sisquoc shale, usu- 
ally mapped as ' ' Santa Margarita ' ' shale, is exposed along the coast from 
Gaviota Beach to the mouth of Jalama Canyon. This is the youngest 
formation exposed on the coast. The maximum thickness, about 3200 feet, 


is exposed in the syncline north of Point Conception, where the section 
is as follows : 

Top of section eroded 

Cream-white massive to poorly bedded somewhat punky silty 

diatomite with conchoidal fracture SOO feet 

Light brownish gray massive to poorly bedded silty to diatoma- 

ceous claystone, crumbly, with spheroidal fracture 1400 feet 

Light brownish gray well-bedded clay shale with splintery frac- 
ture, to laminated thin-bedded siliceous shale with platy 
fracture 1000 feet 

Brown massive compact sandy siltstone, highly bituminous ; 
disappears west of Cojo Canyon ; between Cuarta and Gaviota 
Canyons contains lenses up to 75 feet of well-bedded breccia- 
conglomerate composed of Monterey cherty shale debris in 
tar-soaked sandstone matrix 0-100 feet 


Monterey porcelaneous shale 

Wells drilled throughout the San Rafael foothills encounter the 
Sisquoc formation below the Careaga sand. Cores indicate the Sisquoc 
here to consist of massive light-gray diatomaceous siltstone or shale grad- 
ing upward into Careaga sand and lying unconformably on previously 
tilted and folded Monterey shale. The Sisquoc thins rapidly from Los 
Alamos syncline by successive buttressing out of the lower portion to an 
average thickness of about 300 feet in the northeastern part of the area. 
Here only the upper portion is present; it lies directly on Cretaceous 
or Franciscan rocks. The Sisquoc is exposed only at Birbent Canyon 
where it is upturned along the Little Pine fault. Here the Sisquoc con- 
sists of about 150 feet of white diatomaceous siltstone grading upward 
into Careaga sand and lying on serpentine. 

The Sisquoc formation, like the underlying Monterey, is remarkable 
for the great amount of diatom tests and remains of other siliceous organ- 
isms which make up such a large part of it. Within the area mapped the 
Sisquoc consists of an admixture of diatom debris and clay, in varying 
proportions, deposited under an open sea. Tuffaceous material occurs in 
small amounts. Unlike the Monterey formation, silicified layers are rare 
in the Sisquoc except locally. Calcareous material and calcareous fora- 
miniferal remains are scarce. 

The lower 1000 feet of the Sisquoc formation is assigned to the Del- 
montian stage of upper Miocene, and the remainder to lower (and per- 
haps middle) Pliocene, on the basis of meager foraminiferal faunas 
found in wells, and also upon molluscan faunas found in the sandy f acies 
at Foxen Canyon north of the area mapped.^^ 

Foxen Claystone 

The Foxen formation consists of about 800 feet of claystone lying 
conformably between the Sisquoc diatomite below and the Careaga sand 
above. Within the area mapped the Foxen crops out only in the western 
Purisima Hills in northern Lompoc quadrangle ; the best exposure is at 

" Woodring, Bramlette, and Lehman, op. cit., pp. 1350-1351. 


the tA-pe locality 1^ miles south of Harris. From the Purisima Hills the 
Foxen dips under Los Alamos Valley and extends northward to Santa 
Maria Valley. The formation wedges out down the south flank of the 
Purisima Hills, and also eastward along strike on the north flank. 

At the type locality the Foxen formation is about 800 feet thick and 
consists of light-gray massive claystone and siltstone containing fairly 
abundant diatom and foraminiferal remains. Northwest along the strike, 
just off the map, thin beds of buff sandstone containing phosphate pel- 
lets appear. The Foxen formation reaches its maximum development 
under Santa Maria Valley, where it attains a thickness of 2300 feet. 

The relationship of the Foxen claystone to the Sisquoc diatomite is 
fairly sharp but conformable, although an unconformity on the south 
flank of the Purisima Hills is suggested by overlap of the uppermost 
Sisquoc by the Foxen. Throughout all exposures the Foxen grades 
upward into fine sands of the lower Careaga. Under the San Rafael foot- 
hills the Foxen formation may be represented by the thin transitional 
beds between the Sisquoc diatomite and Careaga sand, but is not recog- 

The restricted areal distribution of the Foxen claystone probably 
indicates that it was laid dovna. under an embayment opening on the 
northwest into the ocean via Santa Maria Valley. Elsewhere the region 
mapped was apparently uplifted as indicated by the regional uncon- 
formity between the Sisquoc and Careaga formations. 

On the basis of foraminiferal f aunules the Foxen formation has been 
assigned to middle and upper Pliocene.^^ 

Careaga Sand 

The Careaga formation is a marine sand of upper Pliocene age lying 
conformably below the terrestrial Paso Robles formation and above 
Foxen, Sisquoc, or Monterey formations. The Careaga sand is present, 
either exposed or buried, throughout virtually all of the Santa IVIaria 
Basin with the exception of Burton :\Iesa. It crops out on both flanks of 
the Purisima Hills, north flank of the Santa Rita Hills, and southwest of 
Lompoc. It also crops out east of Santa Ynez where it extends beyond 
Los Olivos quadrangle and was mapped by Nelson ^^ as the Fernando 
formation. Under Lompoc Valley fossiliferous Careaga sand is encoun- 
tered below aUuvium in water wells. It is deeply buried under upper 
Santa Ynez Valley and the San Rafael foothiUs, but crops out northwest 
of Birbent Canyon. 

Like the Foxen claystone, the Careaga sand attains its maximum 
development under Santa Maria Valley, where it is some 1400 feet thick. 
Under Los Alamos Valley it is probably about 1000 feet thick. It is about 
700 feet thick in the Purisima and Santa Rita Hills, and about 300 feet 
thick in the exposures east of Santa Ynez. 

The Careaga sand is well exposed along the north flank of the 
Purisima Hills, especially at the type locality 2 miles south of Careaga 
station. Here the Careaga is about 725 feet thick and consists of two 
members, as follows : 

«Woodring, Bramlette, and Lohman, op. cit., 1354-1355. 
"Op.cit., pp. 372-374. 


Paso Robles formation 


Upper Careaga (Graciona mentlcrj 

Loose medium-grained gray-white sand 150± feet 

Same as above, but with abundant well-rounded pebbles up 
to 2 inches in size of quartzite, porphyritic igneous rocks, 
and Monterey chert and shale ; local occurrences of fossil 

pelecypod reefs 50± feet 

Hard calcareous sandstone reef with abundant Dendraster 

ashleyi; (Dendraster reei) 0-10 feet 

Lower Careaga (Cehada memher) 

Friable massive yellow-buff fine-grained sandstone 400± feet 

Semi-friable well-bedded buff very fine-grained sandstone 

and minor interbeds of sandy siltstone 125± feet 

Gradational contact 
Foxen claystone 

These two members are mappable throughout most of the Purisima 
and Santa Rita Hills. However, only the upper member is present in the 
Purisima Hills east of Zaca Creek and east of Santa Ynez. In the former 
area no fossils are present and it is possible that some of the sand mapped 
there as Careaga may belong to a younger formation. In the latter area 
the Dendraster reef marks the base of the Careaga sand. 

The lower Careaga member is persistently fine and even grained, 
and was probably deposited under calm shallow waters of a protected 
bay similar to that in which was deposited the Foxen claystone, but more 
extensive. The lower Careaga was thus laid down under transgressing 

The upper Careaga member is a littoral or beach-sand deposit of 
varying lithology. The pebble bed at the base of this member is very 
persistent and indicates a widespread break in sedimentation. The basal 
Dendraster (sand dollar) reef indicates deposition under very shallow 
water. At Cebada and Purisima Canyons the upper Careaga contains 
very thick, irregular lenses of crossbedded coarse sand, often pebbly, 
calcareous, fossiliferous and hard. These v/ere probably deposited as 
sand bars. The uppermost portion of the upper Careaga generally con- 
sists of as much as 300 feet of loose sand devoid of pebbles or fossils, 
which appears to be wind-blown dune sand. The upper Careaga sand was 
deposited under a widespread but very shallow embayment under which 
nearly the entire Santa ]\Iaria Basin was submerged. It represents the 
final stage of marine deposition in this area. 

The relationship of the Careaga sand to the underlying Foxen clay- 
stone is conformable in the northwestern Purisima Hills. However where 
the Careaga sand lies on Sisquoc or Monterey formations, such as in the 
eastern Purisima Hills and Santa Rita Hills and eastward, the relation- 
ship becomes a widespread unconformity, for the most part with angular 
discordance. Under the San Rafael foothills and at Birbent Canyon the 
Careaga sand seems to grade downward into the Sisquoc diatomite, 
despite the absence of the Foxen claystone. The relationship of the 
Careaga sand to the overlying Paso Robles terrestrial beds is everywhere 
conformable, and locally difficult to determine ; but the base of the latter 
is usually marked by the first appearance of white marl followed by clay. 

The Careaga sand contains a large molluscan fauna. The following 
are the more important species occurring in both members. Those marked 
with an asterisk (*) are more abundant in the lower Careaga; those 
unmarked, in the upper Careaga : 



* Lucina cf. annulata 
Macoma cf. nasuta (Conrad) 

* Pecton (Lyropcpten) cerrosensis Gnbl) 

* Pecten (Patiuopecten) healeyi (Arnold) 
Pseudocardium cf. densatum (Conrad) 
"Venerupis" cf. hannibali 

* Yoldia cf. cooperii Gabb 

Drillia graciosana Arnold 
Xassa monmiaiia Martin 
Olivella biplicata 

* Trochita radians Lamarck 

* Turritella gonostoma hemphilli 

Dendraster ashleyi 

On the basis of this fauna. AYoocTring ^^ assigns the Careaga sand 
to upper Pliocene, correlative with the San Joaquin formation of San 
Joaquin Valley. 

Paso Robles Formation 

The Paso Robles formation is a series of terrestrial gravels, sands, 
and clays of probable uppermost Pliocene and lower Pleistocene age lying 
conformably on the Careaga sand. Like the Careaga sand, the Paso Robles 
formation is present throughout the Santa Maria Basin, with the excep- 
tion of Burton Mesa. It is most extensively exposed in the San Rafael 
foothills where it attains a maximum thickness of some 4500 feet along the 
northeastern portion of these hills adjacent to the San Rafael Mountains. 
To the southwest it gradually thins to about 2000 feet in the A^cinity of 
Los Alamos Valley, and to about 700 feet under Santa Rita Valley. It 
is absent under Lompoc Plain. 

Poorly consolidated gravels, sands, and pebbly clays or. silts con- 
stitute the Paso Robles formation. The gravels are usually cross-bedded, 
light gray, and in most areas are made up almost entirely of white shale 
pebbles derived from the ]\Ionterey shale. Sands are generally buff and 
well bedded, often pebbly. Clays and silts are massive to bedded, usually 
greenish but locally light reddish, and commonly pebbly. 

There is no defined sequence in the Paso Robles formation, but in 
general clays and silts predominate in the lower portion and gravels in 
the upper, which becomes coarser toward the top. 

In the San Rafael foothills the lower 2000 feet of Paso Robles 
generally consists of greenish-gray clays and minor white shale pebble 
gravels. VTest of Zaca Canyon a member of loose massive sand constitutes 
the lower 700 ±: feet of Paso Robles. The upper portion of the Paso Robles 
is made up largely of gravels which become increasingly coarse toward 
the top of the formation. These gravels are made up of ^Monterey white 
shale pebbles, but adjacent to the Franciscan exposures of the San Rafael 
Mountains, Franciscan debris becomes increasingly abundant toward the 
top and makes up the entire content of the uppermost portion. 

On the north flank of the Purisima Hills the Paso Robles formation 
consists of about 2000 feet of white shale pebble gravels with some clays 
in the lower portion. A prominent white freshwater limestone bed up to 
3 feet thick occurs near the base in the basal clay member. A similar lime- 
stone bed, as much as 12 feet thick, known as Los Alamos limestone, 
occurs 1200 feet higher. Both these limestone beds contain small fresh- 
water fossils. 

*■? Woodring, Bramlette, and Lohman, op. cit., p. 1358. 



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In the vicinity of Santa Rita Valley the Paso Robles consists of clays 
and gravels with several lenses of loose, windblown sand. 

Orcutt Sand 

The Orcutt formation ranges from less than a foot to 150 feet in 
thickness. It consists of nonmarine sand and gravel resting discordantly 
on the Paso Robles and older formations, and has been assigned to 
middle or upper Pleistocene. The type area is on the north flank of the 
Casmalia Hills west of Orcutt, north of the area mapped. 

The Orcutt formation is extensively exposed in the vicinity of 
Lompoc Valley and Burton Mesa, and on top of the western Purisima 
Hills. In these areas it reaches a maximum thickness of 150 feet and 
consists of loose, medium-grained massive light-buff sand, probably 
deposited by wind blowing from the ocean beach to the west. The top of 
this sand is locally indurated by iron oxides into hard reddish-buff sand- 
stone. The basal portion contains numerous well-rounded pebbles of 
quartzite, acidic igneous rocks, and JMonterey chert and shale. 

The Orcutt formation lies unconformably on older formations which 
have been previously folded, but is itself only gently tilted toward 
Lompoc and Santa Rita Valleys. It is tilted as much as 25° in the latter. 

Terrace Deposits 

In the Santa Ynez Valley and along valleys of the main streams are 
several stream-laid terrace gravels, some as much as 75 feet thick. In the 
Santa Ynez Valley the oldest and most extensive is tilted as much as 15° 
and may be the equivalent of the Orcutt formation farther west. This can 
best be seen on the road east of Solvang. Several younger terraces are 
prominent along the course of the Santa Ynez River. 

Along the coast are terrestrial gravels apparently deposited on the 
wave-cut terraces. The low coastal plain which extends back to about 
two miles from shore is covered with stream-laid cobble-gravel, silt and 
sand as much as 75 feet thick. On the highway 1 mile west of Gaviota 
and also at Alegria Canyon, the basal portion contains fossiliferous 
beach sand. Small remnants of higher, elevated terrace deposits are found 
locally along the coast. 


All stream-laid vallej' fills of Recent age are mapped as alluvium, 
which consists of unconsolidated loam}^ clays, silts, sands, and gravels, 
totaling as much as 170 feet in thickness. 

The thickest and most extensive alluvial fill underlies Lompoc Plain. 
Water-well logs indicate that the upper 120 feet of alluvium on this flat- 
land consists of sand and clay and minor amounts of gravel, and the lower 
50 feet of water-bearing gravel. J. E. Upson ^^ has prepared a subsurface 
map and cross-sections based on logs of water Avells drilled in Lompoc 
Plain, which show that the upper 120-foot member underlies the entire 
plain, but that the lower 50-foot gravel member is present mainly in the 
northern portion, and in the extreme eastern and western portions is 
restricted to the vicinity of the Santa Ynez River channel. It is interest- 
's Upson, J. E., Thomasson, H. G. Jr., and others, Geology and water resources of 
Santa Ynez River valley, Santa Barbara County, California : U. S. Geol. Survey dupli- 
cated rept, pis. 507, 508, June 1947. (Final report in press.) 

1950] STRUCTURE 51 

in2 to note that throuslioiit the areal extent of this gravel the base is 
approximately 170 feet below the ground surface, and is consequently 
below sea level under much of Lompoe Plain, and even extends out to 
sea for an unlmown distance beyond the mouth of the Santa Ynez River. 
This condition indicates subsidence during Recent time, or as Upson ■^^ 
believes, a rise of sea level following the late Pleistocene Wisconsin glacial 

Between Lompoe and San Lucas bridge the alluvium along the Santa 
Ynez River floodplain is similar to that of Lompoe Plain but thinner, the 
upper member being about 40 feet thick, and the basal gravel member 
about 25 feet thick. 

In upper Santa Ynez Valley, Los Alamos Valley, and level-bottomed 
canyons of the San Rafael foothills the alluvium is indistinguishable 
from terrace gravels and the Paso Robles formation, but contains con- 
siderable water-bearing gravel. 

The alluvium which fills flood-plains of the major streams of the 
Santa Ynez ^fountains and Purisima Hills is less than 100 feet thick, and 
consists mainly of loamy silt with minor amounts of sand and gravel. 
Along the coast this alluvium extends below sea level and out to sea 
beyond the mouths of the canyons. 


Southwestern Santa Barbara County comprises parts of four major 
structural provinces. These are, starting from the south: (1) Santa Ynez 
Mountain uplift: (2"^ Lompoe lowland; (3^ Los Alamos syncline; and 
(4) San Rafael Mountain uplift. 

The Santa Ynez Range is made up of a very thick Cretaceous-Terti- 
ary sedimentary section uplifted along the Santa Ynez fault and by 
geantielinal folding. 

The Lompoe lowland is an area of low relief, comprising Burton 
Mesa and Lompoe Valley, which wedges out eastward through Santa 
Rita Valley and lower Santa Ynez Valley. This lowland wedge is in part 
structurally synclinal but is regionally a ' ' high ' ', in which the Franciscan 
basement is relatively close to the surface and covered by a thin, little- 
disturbed sedimentary section. This thin-blanketed wedge separates the 
thick-blanketed Santa Ynez Mountains on the south from the tMck- 
blanketed Los Alamos s;^Ticlinal area on the north. 

Los Alamos syncline is a deep structural downwarp traversing Los 
Alamos and upper Santa Ynez Valleys. It is developed where the Terti- 
ary-Quaternary section of Santa Maria Basin attains its maximum 
thickness. This trough is flanked by the Purisima Hills on the south and 
the San Rafael foothills on the northeast, both of these being anticlinal 
uplifts developed where the sedimentary section thins rapidly from the 
deep s^Ticlinal trough. 

The San Rafael Mountains have been uplifted largely by faulting 
along the southwestern base. 

Nearly all axes of folds throughout the region mapped trend slightly 
north of west, indicating crustal shortening at right angles to that trend. 
This shortening apparently resulted from a regional stress system of com- 
pressive forces acting from a north-northeast south-southwest direction. 

*3 Upson, J. E., Late Pleistocene and Recent changes of sea level along the coast 
of Santa Barbara Countj-, California : Am. Jour. ScL, vol. 247, no. 2, pp. 94-115, 1949, 



[Bull. 150 































































































































































1950] STRUCTURE 53 

The forces may have been directly opposing, but oblique-slip movement 
along many of the eastward trending faults in the Santa Ynez Mountains 
suggests a local counter-clockwise rotational force. 

The various sedimentary^ provinces within the region mapped have 
reacted in various ways to the regional stress. Synclinal deeps such as Los 
Alamos syncline have resisted compression. This is true also of regional 
"highs" such as the Lompoc lowland, indicating that the Franciscan 
basement resisted compression. Areas of least resistance and greatest 
deformation are those in which the sedimentar}'- section thickens or thins 
between these two extremes. 

Santa Ynez Mountains 

The western Santa Ynez Mountains consist of a northern and a south- 
ern structural block separated by the eastward-trending Santa Ynez- 
Pacifico fault zone. 

Southern Structural Block 

The southern structural block comprises the higher Santa Ynez 
mountain range extending eastward from Gaviota Canyon, and also the 
low ridge extending westward through the hills south of Jalama Canyon. 

The higher Santa Ynez mountain range is a block consisting of a 
southward-dipping homocliue in a very thick Cretaceous-Tertiary sedi- 
mentary series uplifted along the Santa Ynez fault on the northern 
base. The crest of this range is essentially a strike-ridge trending par- 
allel to the Santa Ynez fault at a distance of about 1^ miles south of it. 
This mountain block is abruptly terminated on the west by the south 
branch of the Santa Ynez fault extending from Gaviota Pass southwest 
to the mouth of Alegria Canyon. Gaviota Gorge is an antecedent canyon 
cutting through the extreme western portion of this uplifted block. 

The low mountain ridge extending from Las Cruces westward to a 
point south of Jalama Canyon is a structural block similar to that of 
the higher Santa Ynez Range. It consists of a southward-dipping homo- 
cline in a slightly thinner Cretaceous-Tertiary sedimentary section, and 
is uplifted on the north along three faults, namely, the Santa Ynez 
(north branch), Gaviotito, and Pacifico faults. The crest is likewise a 
strike-ridge, but is broken at Santa Anita Canyon by the Pacifico fault. 
This homoclinal block in part forms the south flank of the Pacifico anti- 
cline which comes into it from the northwest at Santa Anita Canyon, 
and also the south flank of the Jalama anticline, coming in from a simi- 
lar direction at Jalama Canyon. 

Northern Structural Block 

The northern structural block of the western Santa Ynez Mountains 
takes in that portion lying north of the Santa Ynez-Pacifico fault zone, 
including the Santa Rosa Hills, Santa Rita Hills, and Tranquillon Moun- 
tain ridge. The stratigraphic section of this northern block is about the 
same as that of the southern block, but is considerably thinner, and 
broken by six, possibly seven unconformities, indicating that the area 
was subjected to that many periods of deformation, uplift, and erosion. 
Consequently the structure is extremely complex. Details are shown on 
the areal geologic map and cross-sections. In general, the structure is 
one in which numerous minor folds, trending roughly N. 75° W., are 
developed in the Miocene formations, on the whole amounting to an 


anticlinorum. The older formations are compressed into several large 
folds with a similar trend, but these formations dip regionally to the 
south so that successively older formations underlie the Miocene from 
south to north. 

The structure of the San Lucas-Wons Canyon area is that of a homo- 
cline in Lower Cretaceous and Eocene sediments dipping steeply north. 
These sediments are unconformably overlain by the Monterey shale, 
which in general dips away from them on both sides. The southwestern 
contact is possibly a fault contact, but evidence is not conclusive. It is 
therefore mapped as an unconformity like the northern contact. 

Santa Ynez Fault System 

The Santa Ynez fault and lesser faults associated with it constitute 
an active fault system of great magnitude, movement along which is 
largely responsible for the uplift of the Santa Ynez Mountains. From 
Gaviota Pass the Santa Ynez fault has been traced eastward continu- 
ously along the northern base of the high Santa Ynez mountain range 
for more than 65 miles into Sespe Canyon, Ventura County. The south 
block is up along the entire course and the throw amounts to several 
miles. Westerly from Gibraltar Dam the fault dips steeply south ; farther 
east it becomes vertical; at Matilija Canyon it dips north. 

The Santa Ynez fault is marked by a zone of gouge and crushed 
rock, often several hundred feet wide. The fault is well expressed topo- 
graphically, as it in most places forms the base of the steep north slope 
of the Santa Ynez mountain front. It is generally marked by a topo- 
graphic depression between this mountain front and the lower hills to 
the north, and is locally followed by streams emerging from the Santa 
Ynez Mountains. 

A component of horizontal or lateral movement along all members 
of the Santa Ynez fault system in which the south block has moved rela- 
tively eastward, is strongly suggested by topographic, structural, and 
stratigraphic relations. West of Gaviota Pass the Santa Ynez fault 
divides into several faults of relatively small magnitude, all having the 
same trend and movement as the main Santa Ynez fault. The Pacifico 
fault is part of the Santa Ynez fault system. 

From regional mapping it is concluded that the Santa Ynez fault 
system is a deep-seated zone of recent activity, trending eastward for a 
total distance of more than 80 miles. Oblique-slip movement of great 
magnitude has taken place along this zone ; the southern block has been 
uplifted to form the Santa Ynez Range and has moved eastward rela- 
tive to the northern block. 

Santa Ynez Fault. Within Los Olivos quadrangle east of Quiota 
Canyon the Santa Ynez fault is composed of two closely spaced faults. 
The southern of these is the main Santa Ynez fault, which brings Eocene 
and Upper Cretaceous of the Santa Ynez mountain block on the south 
against Rincon-Vaqueros-Sespe on the north. At AVons Canyon this fault 
dips as low as 15° S., but to the east and west the dip steepens to near 
vertical. The northern fault is vertical and follows a straight course, 
bringing Rincon-Vaqueros-Sespe on the south in contact with Monterey 
shale (which lies directly on the Espada formation and serpentine at 
San Lucas and Wons Canyons) on the north. Between Quiota Canyon 
and Gaviota Pass the Santa Ynez fault is a single fault which brings the 
Jalama formation on the south against Rincon shale on the north, with 
a throw amounting to about 2 miles. 

1950] STRUCTURE 55 

Throughout Los Olivos quadrangle the Santa Ynez fault shows some, 
though not conclusive, evidence of a horizontal or lateral component of 
movement, the south block having moved relatively eastward. Such move- 
ment, in which the block opposite the observer moved relatively to the 
left, is termed left-lateral displacement by Hill.^° Topographic evidence 
of lateral movement on this fault is suggested by so-called "rift" topog- 
raphy along its course ; that is, a general topographic depression locally 
followed by streams and marked by notches through hills crossed by the 
fault. Such topography is characteristic of recently active strike-slip and 
oblique-slip faults in California. Evidence for left-lateral movement 
along the Santa Ynez fault is indicated by offsetting of some canyons 
emerging from the north slope of the Santa Ynez Range, such as Quiota 
Canyon, which follow the fault always in a westerly, never an easterly, 
direction, before resuming their northward course. Structural evidence 
of left-lateral movement is suggested by the intersection of folds in the 
northern block always from a northwesterly, never a northeasterly direc- 
tion, indicating left-lateral horizontal drag. Near-horizontal grooves have 
been found in the fault gouge, where it is exposed on Highway 101 near 
Gaviota Pass, and also in a minor parallel fault-plane on the old highway 
half a mile east of Gaviota Pass. Stratigraphic evidence of left-lateral 
movement along the Santa Ynez fault is suggested by the great difference 
of the stratigraphic section on either side of the fault at San Lucas and 
TTons Canyons. The mountain block on the south is made up of at least 
15,000 feet of Upper Cretaceous, Eocene, Oligocene, and lower Miocene 
sediments, which do not appear on the northern block where Monterey 
shale directly overlies Lower Cretaceous or Upper Jurassic, but which 
are present west of Quiota Canyon. This stratigraphic anomaly may be 
explained by a great amount of left-lateral .strike-slip displacement along 
the Santa Ynez fault. 

Santa Tnez Fault, South Branch. At Gaviota Pass the Santa Ynez 
fault di^^des in two, from which point the south branch extends south- 
westward to the ocean at the mouth of Alegria Canyon. Displacement 
decreases rapidly from Gaviota Pass and the fault supposedly dies out 
under the sea. This fault appears to dip about 60 ~ X., and movement has 
been upward on the southeast side, although some apparent reversal of 
throw is indicated at Alegria Canyon. However, this condition may be 
due to possible left-lateral movement. A hot sulfur spring issues from 
the fault south of Las Cruces. 

Santa Ynez Fault, Xorth Branch. From Ga^dota Pass the steep- 
dipping north branch of the Santa Ynez fault extends westward for 
about 6 miles. Movement was upward on the south side of the fault, the 
maximum displacement being about 5000 feet. Displacement decreases to 
the west and the fault becomes a south-dipping thrust which dies out into 
the overturned axis of the Pacifico anticline. 

Pacifico Fault. About half a mile sotith of where the north branch 
of the Santa Ynez fault dies out the movement is taken up by the Pacifico 
fault. This is the largest fault west of Gaviota Canyon, trending from 
Agua Caliente Canyon west for about 10 miles to Jalama Canyon. Santa 
Anita Creek flows eastward for some 3 miles along this fault before turn- 
ing south. The east-trending portion of Santa Anita Canyon is known as 
the Pacifico, from Avhich this fault was named. Movement has been 

»Hill, M. L., Classification of faults: Am. Assoc. Petroleum Geologists Bull., vol. 31, 
no. 9, p. 1670, 1947. 


upward on the south side of the fault, which dips very steeply south, and 
attains a maximum throw of about 5000 feet at the upper Pacifico. Here 
it splits into two closely spaced faults, which die out toward the west 
into the Jalama Canyon anticline. A left-lateral component of horizontal 
niovement along this fault is suggested by associated folds on the north 
side, which intersect it from the northwest. 

At the head of Bulito Canyon immediately south of the Pacifico fault 
are three small cross-faults subsidiary to the Pacifico fault, each with 
right-lateral displacement. The Jalama sandstone bed between these 
faults strikes N. 60° E., which is anomalous to the normal easterly strike. 
This condition suggests that these are small fault blocks rotated counter- 
clockwise by probable left-lateral horizontal drag along the Pacifico 

Bulito Fault. South of the Pacifico fault is a small vertical strike 
fault referred to as the Bulito fault, traceable for about 3 miles. It is 
difficult to recognize as it is so nearly parallel to the beds, but is clearly 
indicated by partial repetition of the Cozy Dell and Matilija formations. 
Left -lateral displacement is suggested by offset contacts. 

Gaviotito Fault. From the Pacifico fault in the Pacifico. the Gavio- 
tito fault branches off and extends north of east for about 4 miles. It dips 
steeply, and the south block has been elevated and moved eastward rela- 
tive to the north block, as indicated by oft'set contacts and the offsetting 
of the axis of the Pacifico anticline. 

Cojo Fault. The Cojo fault is a small north-dipping thrust fault 
about 4 miles north of Government Point. It is traceable for about 2 miles 
and appears to dip about 45° N. Offset contacts suggest left-lateral dis- 
placement whereby this fault may be related to the Santa Ynez fault 

Other Faults in the Santa Ynez Mountains 

Canada Honda Faidt. Traceable from Point Pedernales for about 
6 miles eastward up Cafiada Honda, is the Caviada Honda fault. This 
fault dips steeply south, and has a maximum throw of about 3000 feet, 
which brings Jurassic, Cretaceous, and Eocene rocks on the south against 
Monterey shale on the north. The latter formation is tightly crumpled 
into numerous sharp folds which intersect the fault from a northwesterly 
direction. This relationship indicates left-lateral horizontal drag along 
the fault, the south block having moved relatively eastward as well as 

Santa Rita Faults. Some distance farther east, but in line with the 
Canada Honda fault, are three small en echelon faults trending about 
N. 75° E. for some 3 miles in the Santa Eita Hills. These are the Santa 
Eita faults, similar to the Caiiada Honda fault but of less magnitude. 
The largest brings Monterey shale on the south against Sisqnoc diatomite 
on the north. Here the Monterey shale is tightly compressed into folds 
intersecting the fault at a sharp angle from the east. This condition, as 
well as offset contacts, indicate left-lateral horizontal movement along 
these faults as along the Canada Honda fault. 

Much of the intervening area between the Santa Eita and Canada 
Honda faults is a line-up of tightly compressed small closed anticlines en 
echelon in the Miocene, and trending about N. 75° W. The Caiiada 
Honda and Santa Eita faults and the intervening and associated sharp 


1950] STRUCTURE 57 

folds -were developed along a zone of oblique-slip movement ; the sontliern 
block moved upward and eastward relative to the northern block, in a 
manner exactly similar to the Santa Ynez fault system, but on a smaller 

Faults in TranquiUon Monniain Area. Near Honda School in 
Canada Honda is a small fault that trends northeast for about 2 miles. 
Offset contacts indicate movement along this fault to be left-lateral, the 
southeastern block having moved relatively nortlieastward. 

Between Caiiada El ]\Iorida and Caiiada El Jolloru are three minor 
vertical faults trending about N. 75° E. ; upthrow has been on the south 
side, in each ease. 

Two very old faults have been found near TranquiUon Peak. A 
mile east of this mountain is a northwest-trending fault which brings 
Espada shale on the southwest against Gaviota standstone on the north- 
east. The Vaqueros and TranquiUon formations extend right over this 
fault, without being cut by it. This fault was therefore active after 
deposition of the Gaviota but before the Vaqueros was deposited. It is 
believed to extend about 2 miles in both directions from the portion 
exposed but is concealed by the ]\Iiocene formations. The other fault, half 
a mile southwest of the peak, trends eastward. It brings Espada shale on 
the south against Eincon shale on the north, but the TranquiUon rhyolite 
flow extends directly over it. unaffected. It is therefore younger than the 
Rincon and older than the TranquiUon in age. 

Faults in Santa Rosa-No joqui-Alisal Rills. Just north of the Santa 
Rosa ridge is a steep, probable reverse fault that trends eastward for about 
5 miles. Movement has been upward on the south side of the fault : max- 
imum throw has been about 2500 feet. Left-lateral horizontal movement 
may have taken place, as suggested by the axis of the Santa Rosa anti- 
cline which intersects it from the southwest. South of Alisal ranch are 
three minor reverse faults that dip south. 

Throughout much of the Santa Rosa Hills and Xojoqui-Alisal area 
are numerous steep normal faults, all upthrown on the north side. They 
are minor faults, more or less equally spaced ; they show no evidence of 
horizontal movement, and no relationship to the folding in the area. 
These faults are difficult to account for, but a possible explanation is that 
they constitute a series of northward-tilted blocks caused by differential 

Befugio Fault. The Refugio fault extends from Tajiguas Canyon 
eastward for about 6 miles to Capitan Canyon. It is well exposed at 
Refugio Canyon where it causes repetition of the Vaqueros sandstone. 
Here it dips 52° N., being a normal fault with about 500 feet of maximum 
vertical displacement. A similar normal fault, with only 100 feet of throw, 
occurs farther west in the Gaviota sandstone at San Onofre Canyon. 

Erhuru Fault. A north-dipping normal fault known as the Erburu 
fault forms in part the northern limit of production at Capitan oil field. 
It is exposed on the east side of Corral Canyon in the excavation at the 
Shell Company Xo. ''Covarrubias" 1-37 well, where it dips about 50° N. 
Thrusting has been from the north, as the flat-lying Rincon shale is 
turned up adjacent to the fault, so that the shale dips south. This anomaly 
may be the result of horizontal movement along the fault. Associated 
folding suggests that the south block moved relatively eastward. West 


of Corral Canyon the fault dies out into an anticline. To the east it is 
concealed by terrace deposits ; but it may be the continuation of the fault 
exposed in Las Yeguas Canyon north of U. S. Highway 101, just east 
of the area mapped. At Corral Canyon the Erburu fault brings flat-lying 
Rincon shale on the south against north-dipping Monterey shale on the 

Las Yeguas Fault. Las Yeguas fault is well exposed on the sea cliff 
1 mile east of Capitan. It is a reverse fault dipping about 60° N., bringing 
Rincon shale on the north against Monterey shale on the south. Offset 
contacts indicate probable horizontal movement, the south block having 
been displaced relatively eastward. 

Lompoc Valley and Burton Mesa 

The structure of Lompoc Valley and Burton Mesa is very simple, 
compared to that of the Santa Ynez Mountains. Wells drilled thoughout 
this lowland area pass through a comparatively thin blanket of Orcutt, 
Careaga, Sisquoc, and Monterey formations probably aggregating not 
more than 4000 feet in maximum thickness, and then directly into Fran- 
ciscan rocks. The structure of the Tertiary section under Lompoc Valley 
is apparently a flat, voidisturbed but broadly warped synclinal area. 
Orcutt sand is exposed around the valley but w^ater wells in the level 
portion of the valley encounter fossiliferous sands of the Careaga below 
terrestrial deposits at a depth of about 175 feet. Monterey shale is 
exposed over a large part of Burton Mesa, which is a broad anticlinal 
upwarp, and along the shore line northward from Surf. This upwarp 
comprises many gently undulating folds with axes trending on the 
average N. 75° W. 

The Lompoc Valley-Burton Mesa area is apparently a broad, wedge- 
shaped area widening seaward, of Franciscan rocks whose structure is 
unknovm, covered by a thin blanket of middle and late Tertiary and Qua- 
ternary sediments. This block was apparently stabilized by pre-Monterey 
orogenies so that it resisted deformation and uplift during the great 
Pleistocene orogeny, and therefore remained as a very slightly disturbed 
lowland area. It extends an unknown distance out to sea, but to the east 
wedges into the narrow Santa Rita and low^er Santa Ynez Valleys, which 
geologically form a part of it. 

Lompoc oil field is located on a large, broad, closed anticline devel- 
oped along the northeast edge of the Lompoc lowland wedge. This fold 
is not exposed at the surface, but eastward it becomes part of the Pur- 
isima anticline which emerges from under the Careaga sand. "Wells 
encounter Franciscan below the Monterey shale at a depth of about 3000 
feet under the Lompoc anticline. The fold is asymmetrical, the south flank 
dipping 5° to 10°, and the north flank about 30°. The dip increases with 
depth on the north flank due to the great thickening of the Sisquoc 
formation doAvn dip. 

Santa Rita Valley and Lower Santa Ynez Valley 

The structure of the Santa Rita and lower Santa Ynez Valleys is a 
broad syncline with Orcutt and Paso Robles formations exposed on the 
surface, and the axis trending about N. 75° W. This synclinal valley area 
is structurally the eastward extension of the thin-blanketed Lompoc low- 
land high, and has like it resisted Pleistocene deformation and uplift. 

1950] STRUCTURE 59 

Purisima Hills 

The Purisima Hills are structurally an anticlinal uplift developed in 
a thick late Tertiary-Quaternary section. This uplift has been formed 
alorn? a belt where the section thickens northward from the thin-blanketed 
Lompoc-Santa Rita-lower Santa Ynez Valle}' high on the south, to the very 
deep, thick-blanketed synclinal trough on the north which follows Los 
Alamos and upper Santa Ynez Valleys. As a result of this condition the 
anticlinal structure of the Purisima Hills is generally asjTnmetric; the 
south flank dips gently, and the north flank dips steeply or is even locally 
overturned toward Los Alamos Valley. 

The main axis of the Purisima anticline trends about N. 75° W. and 
roughly follows the crest of the hills. The structure is highest in the east- 
ern Purisima Hills, where Monterey cherty shale is exposed in the core, 
and Sisquoc and Careaga formations on the flanks. Numerous minor folds 
with axes trending about X. 75^ W. are developed in the Monterey shale 
exposed in this area. The highest of these appears to be the one north of 
Buellton where the Frank Buttram Xo. "Reuben" 1 well passed from 
Monterey shale directly into serpentine at 1400 feet. In the extreme east- 
ern Purisima Hills the anticlinal structure in the ]\Ionterey shale is over- 
lapped by the Careaga sand and later formations, but is believed to plunge 
eastward under Santa Ynez Valley. Southeast of the town of Santa Ynez 
another fold emerges and rises eastward beyond the area mapped. A well 
("X^ational Exploration Co.") drilled on this fold just east of Los 
Olivos quadrangle reportedly bottomed in serpentine below Monterey 
shale at 2665 feet. 

The high portion of the eastern Purisima Hills plunges westward 
into a saddle at Cebada Canyon. From here the axis in the pre-Careaga 
formations extends westward and rises into the concealed Lompoc anti- 
cline of Lompoc oil field. However the axis in the Careaga sand does not 
conform to this fold, but extends northwestward and rises into a sharp 
secondary anticline which exposes Sisquoc shale north of Lompoc field. 
This fold, referred to as the western Purisima anticline is closed, partly 
overturned and perhaps thrust-faulted southward. ]\Ian3^ wells drilled on 
this structure find tliat it dies out at depth into the north flank of the 
Lompoc anticline. 

Faults in the Purisima Hills. The western Purisima anticline 
appears to be cut by a small thrust fault that dips north. Evidence of this 
fault is suggested by the highly sheared and brecciated condition of the 
Sisquoc diatomite along the south edge of the hills hwe. and also by a 
zone of shearing at 2200 feet in Union Oil Company X'o. ''Purisima" 19 
well. Farther southeast are two small thrust faults that dip north at 
Purisima and Cebada Canyons. The westerly of these dips 45° X. with 
about 75 feet displacement. The easterly appears to be steeper, with about 
100 feet of movement. 

All three of these minor thrusts line up and appear to have developed 
where the section thickens rapidly northeastward. 

Los Alamos Valley and Upper Santa Ynez Valley 

The structure underlying Los Alamos and upper Santa Ynez Valleys 
is a major synclinal trough, the axis of which trends about X. 65° W.. and 
passes through the towns of Los Alamos and Los Olivos. This downwarp is 
referred to as the Los Alamos s^Ticline and forms the axis of the Santa 
]Maria structural basin through the mapped area. It is a true synclinal 


downwarp made up of a continuous series of sediments Miocene to Pleisto- 
cene in age, which total some 15000 feet in thickness. 

Along this sj^nclinal trough the warped depositional surface of the 
Paso Robles formation is still preserved in eastern Los Alamos Valley and 
eastern Santa Ynez Valley. 

San Rafael Foothills 

In the San Rafael foothills, an area of gentle uplift, the Paso Robles 
formation is exposed and much dissected by erosion. The structure com- 
prises two major anticlines, separated by a shallow syncline. The western- 
most anticline is the Zaca, a very extensive, closed fold whose axis trends 
about N. 60° W. for more than 12 miles. The Zaca oil field is at its highest 
portion. Surface dips are about 15° on the south flank, 5° on the north 
flank. The easternmost anticline is the San Marcos, whose axis trends 
about N. 50° W. across Figueroa Canyon for some 15 miles, of which 6 
miles lies within Los Olivos quadrangle. Northeast of this anticline is a 
syncline whose northeast flank is largely concealed under the Little Pine 
overthrust. These two folds are believed to cancel each other on the north- 
west under the Little Pine overthrust near Figueroa Canyon. 

Wells drilled throughout the San Rafael foothills find that the struc- 
ture in the Careaga and Sisquoc formations conforms with the surface 
structure of the Paso Robles formation. However, that of the Monterey 
shale does not conform, but generally dips more steeply to the southwest as 
it is overlapped from southwest to northeast by the Sisquoc, at least under 
the Zaca anticline. Local folds also complicate the Monterey structure so 
that details are not known. The Monterey shale is underlain by Cretaceous 
(?) shale and sandstone in this area. Wells drilled on the San Marcos anti- 
cline at Santa Aqueda Canyon pass from Sisquoc directly into Cre- 
taceous ( ?). 

San Rafael Mountains 

The small portion of the San Rafael Mountains lying within Los 
Olivos quadrangle is composed of Franciscan rocks and sill-like masses of 
serpentine, striking due west to N. 60° W., and generallj^ dipping steeply 
to the north. The Franciscan rocks may contain small sharp folds, but are 
so highly sheared and brecciated that it is not possible to work out struc- 
tural details. In the northeast corner of Los Olivos quadrangle the Fran- 
ciscan is overlain directly by Monterey shale that dips steeply to the 

The Franciscan mass of the San Rafael Mountains has been thrust 
southwestward along the Little Pine fault over the Paso Robles formation 
of the San Rafael foothills. This fault dips from 25° to 38°NE at the 
surface. Southeast of the mapped area this thrust fault is traceable for 
some 20 miles along the base of the San Rafael Mountains. It extends 
about 8 miles through Los Olivos quadrangle and dies out into upturned 
Sisquoc and Careaga formations immediately northwest of Birbent 


Jurassic Deposition. The earliest geologic event recorded in south- 
western Santa Barbara County is the rapid deposition under a widespread 
sea of the Upper Jurassic ( ?) Franciscan formation. This series of sands, 
muds, siliceous cherts and basaltic lava flows attained an unknown but 
tremendous thickness. Deposition of the Franciscan was followed by 
deposition of the Honda shale, at least in the Point Arguello area. 


in southwestern Santa ^^^ .^^H^Kmations, and the 

ated condition of .^ot^^^^l^^/''!''^''Xono-hout the former. Neither for- 

numerous serpentinized J^^^^^^Jd S^P^^'^°^*^ ^' ""'^ °''" 

mation, however, was ^^tamorphosed .The^^^^^ disturbance occurred 

erally affected m this manner, ^^f^J.^^^'^", "^^^ deposition of the 

after deposition of the Honda, and probably be^^^^ ^^^^^ 

Espada shale. The shearing and brecci^^^^^^^^^^ 

tectonic forces, but may have ^^^^^^he ^e.ult^^^^^ ^^^^^^. 

and their subsequent physica ^f P^^^^^^/^^^^',^^^ whether or not 

tion to serpentine. The record is too .^^f^^T^^? J^^^'L^^e The Franciscan 
the region emerged from the sea ^^^ ^^^^^^^^^^^^^^^^ after deposi- 

^\^r:^^:i^^t1S^=^~- ^eat Nevadan 

""'^'Taie Jurassic-Early Creiaceo^.Be,osiHonJ^^^^^ 

tion was followed by eonthW ^^^^ ^l ^^l^: Z^. A 

area below sea level. A f.^^^^^^^^^'^':;'^?^ during the close of Jurassic 

sands, the Espada ^rmation,. accumula^ec^^^^^^^^^^^ abundant, as indi- 

and throughout early Cretaceous time Plant le .^^^^^ ^^cal 

cated by the great amount of ^^^^^^^^^^.^^^'^^^^^^^ deposition of 

intrusion of ultrabasic rocks ^^y/^!,^,'^^''^j4^Sees of serpentine in the 

the Espada, as suggested by the l^f^^^^Xcas Canyon. 

lower portion of the Espada formation m San ^^«^«;^^^4,,,^, record 

in the mapped area is not cleaJ^^%^*f J^^^^^f Cm^^^^^^ However the 
not this period is represented ^^ ^J^^f/jf^/^/.^'^ation suggests that 

dence continued along the site of the S^^t J,^^ ^^^^^^^ This sea 
became the northern part of the ^.^fj^ :^^\";;^g ^l,ieh constitute the 
received some 3000 feet of ^'^'^'^'^ ^^J^Zl^^^^ 
Jalama formation. The absence of ^^is formation nortn ^.^^_ 

Mountains suggests that area was ^-^^^-^^Xmconformity between 
Early Eocene ^^/^rmaf^ort^ The i^ lo ^^.^^ ^^^^^ 

the Cretaceous 3^\^}^^-f'l^^.l^^^^^^^ the northern portions 

(or Sierra Blanca limestone where present J d undergone a 

^f the Santa Ynez Mountains indicate^ dtinf earYv Eocene time. This 
period of emergence, uplift^ TlTresuU of the^-reat Laramide orogeny, 
Lturbanceisappajttytbe^^^^^^^ ^^^^ affected includes 

active at the close of <^^^).^'^^'''l^ "^^^^^^ 

not only the northern portion of the ^anta Y nez ^ ^^^.^ ^^^ ^^^ 

can best be studied, but ^^.^Vln^i^^e Xctld area is referred to by Reed 

a Op. cit., p. 13, fig. 6. 


Miocene. Its southern margin, the site of the northern Santa Ynez Moun- 
tains, appears to have underoone a regional tilt to the south. The Santa 
Barbara embayment was unaffected. 

Eocene-Oligocene Deposition. From middle Eocene through early 
Oligocene (Refugian) time, what is now the Santa Ynez Mountains sub- 
sided continuously in the region of the Santa Barbara embayment, in 
which was rapidly deposited a continuous series of sands, silts, and clays 
making up the Anita, Matilija, Cozy Dell, Sacate, and Gaviota formations, 
which attained a total maximum thickness of about 7500 feet. 

During late Oligocene (late Refugian) time sedimentation graduall}^ 
exceeded subsidence in the Santa Barbara embayment so that it became 
filled with sediments, causing partial regression of the sea. Terrestrial 
sands and red silts of the Sespe formation were deposited in the eastern 
portion, which formed a level plain. The area to the west remained sub- 
merged under very shallow water, in which were deposited littoral sands 
of the Alegria formation. Maximum thickness of the Sespe-Alegria sedi- 
ments amounts to about 2000 feet. 

The sediments deposited during Eocene-Oligocene time were derived 
mainly from granite and metamorphic rocks, probably from an area to the 
east, as indicated by their mineral composition and the predominance of 
pebbles of granitic and quartzitic debris. Franciscan debris was deposited 
in only very minor amounts, although it makes up a large part of the Sespe 
conglomerate and red beds deposited in the Alisal-Nojoqui area along the 
southern border of the rising San Rafael uplift. 

Oligocene Deformation. "While the Sespe and Alegria formations 
Were being deposited in the Santa Barbara embayment, the San Rafael 
uplift underwent renewed deformation, uplift, and erosion. This dis- 
turbance, the Ynezan orogeny, probably reached its climax at the close 
of Refugian or beginning of Zemorrian time. The San Rafael uplift, or at 
least that portion now occupied by Burton Mesa and the Purisima Hills, 
rose to a rugged area exposing the Franciscan, which became the source 
of the Sespe-Vaqueros conglomerates deposited along the southern border. 

The effects of the Ynezan orogeny can best be studied along the 
northern Santa Ynez Mountains, where sediments deposited along the 
northern margin of the Santa Barbara embayment become involved. 
Here the Gaviota and older formations became compressed into broad 
gentle folds with axes trending slightly north of west, and near the site 
of Tranquillon Peak some faulting occurred. This is the earliest definite 
record of folding and faulting in the Santa Ynez Mountains. This defor- 
mation was accompanied by emergence, uplift, and erosion. 

Early Miocene Deposition. In Zemorrian (early Miocene) time 
during or immediately following the Ynezan orogeny terrestrial sedi- 
ments derived from the Franciscan San Rafael uplift were deposited in 
the Nojoqui-Alisal area. These make up the Sespe conglomerate and red 
beds of thatarea. Submergence of the entire northern Santa Ynez Moun- 
tain area under a shallow sea transgressing northward from the Santa 
Barbara embayment immediately followed. In this advancing sea was 
deposited coarse gravel, then sand, of the Vaqueros formation, followed 
by fine muds of the Rincon formation as the sea deepened in Saucesian 
(early Miocene) time. 

The San Rafael uplift was not submerged during Zemorrian-Sauce- 
sian time but it contained at least one inland basin which received terres- 
trial sediments of the Lospe formation. 


Early Miocene Deformation. In the very late Saucesian (late early 
Miocene) time another disturbance, the Lompocan orogeny, affected the 
San Rafael uplift, causing- renewed uplift, deformation, and erosion. 
The Lompocan orogeny involved essentially the same portion of the Santa 
Ynez Mountains as that affected by the preceding Ynezan orogeny, 
especially the portion from San Julian Valley westward. Here folds devel- 
oped during the former orogeny became further compressed during the 
latter and involved the Vaqueros-Rincon formations. 

The Lompocan orogeny and its forerunner, the Ynezan orogeny, 
are extremely important in the geologic history of the mapped area and 
perhaps of California, as they brought about a great change in. paleo- 
geography. The Lompocan orogeny is especially significant as it vi'as 
immediately followed by local volcanism, regional submergence, and a 
great change in sediriientation. 

Early Miocene Volcanism. Near the end of Saucesian time the 
Lompocan orogeny was immediately followed by volcanic eruptions of 
rhyolite lava, agglomerate, and ash at the site of Tranquillon Mountain, 
and by local eruptions of basalt lava and agglomerate at the site of the 
Santa Rita Hills. These volcanic and pyroclastic rocks make up the Tran- 
quillon formation and were probably erupted as the region subsided fol- 
lowing the Lompocan orogeny. 

Middle and Late Miocene Deposition. The Tranquillon volcanism 
was accompanied or immediately follow^ed by submergence of the San 
Rafael uplift, so that throughout Relizian, Luisian (middle Miocene) 
and Mohnian (late Miocene) time the entire mapped area was under 
the sea which flooded a large part of California. In this widespread open 
sea deposition of clays continued in early Monterey time but in decreas- 
ing quantities as the nearby laud areas became submerged. Calcium 
carbonate was deposited to form the limestones of the lower Monterey. 
The Monterey sea receiA'cd enormous quantities of siliceous sediment, 
deposited either organically or chemically. All these fine sediments must 
have accumulated very slowly in the open sea at a depth below wave 
and current action. 

Marine life, particularly single-celled organisms, flourished during 
Monterey deposition, and their remains make up a large part of the 
Monterey formation. j\Iuch organic debris settled to the bottom and, 
perhaps because of the great depth of the sea, was not oxidized. It con- 
sequently became buried with the fine sediments, to form petroleum and 
other bituminous matter. 

The sea floor subsided at a more or less uniform rate and received 
an average of about 2000 feet of Monterey sediments. However, subsid- 
ence and deposition became unusually rapid along Los Alamos trough, 
which began to develop as a do^^iiwarp, and received at least 4500 feet 
of Monterey sediments. 

Late Miocene Deformation. Deposition of the Monterey formation 
was followed \)j a local but important disturbance, the Raf aelan orogeny, 
which affected the area northeast of the Santa Maria-Los Alamos trough 
and part of the San Rafael ^Mountains in Delmontian time. The result 
of this orogeny is most evident in the Santa ]\Iaria Valley oil field, as 
indicated by the northward overlap of the Sisquoc formation upon the 
Monterey and Franciscan. A similar condition generally exists south- 
eastward through the San Rafael foothills, as indicated by weUs, from 
which it is evident that this area underwent emergence, uplift, and 


erosion by being tilted regionally to the southwest. Some local folding- 
may have occurred. The Rafaelan orogeny thus has affected the old San 
Rafael uplift, but only the axial portion of it. Other areas throughout '' 

the region mapped were undisturbed, except for slight local uplift at 
the site of the Santa Rita Hills and southern Santa Ynez Mountains. fli 

In the Santa Rita Hills the unconformity at the base of the Sisquoc 
formation and consequent overlap of the upper Monterey shale indicate 
this area to have undergone local uplift and erosion. Evidence that the 
earliest uplift along the site of the southern or higher Santa Ynez Moun- 
tains occurred during the Rafaelan orogeny is suggested by the breccia 
conglomerate containing Monterey chert pebbles at the base of the Sisquoc 
shale west of Gaviota Beach. (ji 

Late Miocene-Pliocene Deposition. The Rafaelan orogeny was fol- 
lowed by deposition of fine sediments of the Sisquoc formation during 
late Miocene and early Pliocene time. Subsidence and deposition were 
continuous and rapid along the Los Alamos trough, which received some 
5000 feet of Sisquoc diatomaceous mudstone. Northeastward from this 
downwarp, the Sisquoc sea transgressed onto the San Rafael axis which 
gradually became buried by diatomaceous clay and silt. % 

During late Miocene (Delmontian) time, the sea between the Los 
Alamos trough and what is now the southern Santa Ynez Mountains 
received about 1000 feet of lower Sisquoc diatomite. This sediment is 
made up almost entirely of diatom tests, indicating a local condition 
extremely favorable for very rapid propagation of diatoms. The very 
low percentage of clastic material in this finely laminated diatomite 
indicates deposition in protected waters, and fish remains found in these 
sediments are mainly shallow-water species. The diatomite of the lower 
Sisquoc was apparently deposited in a shallow, protected area of the 
lower Sisquoc sea ; sheltered perhaps by the local uplift developed during 
the Rafaelan orogeny along the site of the southern Santa Ynez Moun- 
tains which may have persisted through late Miocene time either as a 
very low island or peninsula, or more likely as a submarine ridge. South 
of this uplift, clay and minor amounts of siliceous sediment accumulated 
under an open sea. 

During early Pliocene time, open seas probably existed throughout 
the mapped area, in which were deposited clay, silt, and diatom debris of 
the middle Sisquoc. Near the end of early Pliocene time, diatomite of the 
upper Sisquoc was deposited in the Purisima Hills-Burton Mesa area. 

In middle Pliocene time, subsidence continued in at least the west- 
ern portion of the Los Alamos trough, which received about 1000 feet of 
claystone of the Foxen formation. There is no record of deposition else- 
where in the mapped area during this time interval. 

Late Pliocene Deformation. In late Pliocene time, following or 
perhaps accompanying deposition of the Foxen mudstone, most of the 
area mapped underwent a great regional disturbance, the Zacan orogeny, 
indicated by the widespread unconformity at the base of the Careaga 
sand. This is best seen in the eastern Purisima Hills where the Careaga 
sand laps over the eroded surface of the Sisquoc and Monterey forma- 
tions. During the Zacan orogeny the entire region, with the exception of 
the Los Alamos trough and San Rafael foothill area, underwent wide- 
spread deformation, emergence, and erosion. Both the San Rafael and 


Santa Ynez I\ronntains came into existence by emergence and uplift along 
lines of structural weakness wliich evolved into the present major faults 
in these ranges. The folds formed in the northern Santa Ynez Moun- 
tains during the Ynezan and Lompocan orogenies were further com- 
pressed, and the Monterey-Sisquoc formations became involved in many 
new folds with similar trends. The Burton ]\Iesa and eastern Purisima 
Hills emerged as anticlinal uplifts. 

Late Pliocene-Pleistocene Deposition. The Zacan orogeny was fol- 
lowed by submergence of the entire Santa Maria Basin, with the excep- 
tion of Burton ]\Iesa, in late Pliocene time, under a shallow emba^^uent 
in which was deposited the Careaga sand. Subsidence and deposition were 
most rapid along the Los Alamos trough. 

Toward the end of Pliocene time the Santa ]\Iaria Basin became 
filled with sediments, causing the sea to withdraw, and became a broad 
plain on which terrestrial sediments of the Paso Eobles formation were 
deposited. These were derived from the rising San Kafael and Santa Ynez 
Mountains, and became increasingly coarse as these ranges grew during 
the Pleistocene. 

The Paso Eobles sediments were derived mainly from the San Rafael 
Mountains, and deposition of these alluvial sediments was especially 
rapid along the foot of this range where the formation attains a thickness 
of more than 4500 feet. It progressively thins away from this mountain 
front. This appears to be a case in wliich the weight of rapidly deposited 
sediments actually caused subsidence of the underlying platform. 

Pleistocene Deformation. The increasing growth of the San Rafael 
and Santa Ynez ^fountains culminated in the early Coast Range orogeny 
in the middle Pleistocene, when these ranges probably attained their 
present heights. This great orogeny affected the entire mapped area, 
causing further compression of folds formed by earlier orogenies, and 
the development of many other structures, in which the Careaga and 
Paso Robles formations were involved. The Purisima Hills and San 
Rafael foothills were formed during this disturbance by anticlinal 

The mountains and hills formed during the early Coast Range 
orogeny underwent intensive erosion which is referred to as the ''first 
erosion cycle." This is described in detail under the section headed 
Erosion Cycles. 

The late Pleistocene was a period of relative quiescence, during 
which the elevated areas were worn doT\Ti to the late mature stage of 
erosion and sands of the Orcutt formation were deposited in Lompoc and 
Los Alamos Valleys, and terrace gravels in Santa Ynez Valley and on the 
coastal plain. 

The region underwent renewed deformation and uplift in very late 
Pleistocene and Recent time when it attained its present topography. 
This disturbance is termed the late Coast Range orogeny; during this 
time the area underwent the "second erosion cycle," as described under 
Erosion Cycles. 

The complex structure and resultant physiography of Santa Bar- 
bara County were developed by the series of diastrophic events starting 
with the early Miocene Ynezan orogeny and culminating with Pleis- 
tocene Coast Range orogeny, caused by a recurrent stress system of 
increasing intensity, these events together constituting the local effect 
of the Cascadian revolution. 



Bull. 150 



Figure 6. Structural map of Capitan oil field, Santa Barbara County. 


Oil and Gas 

Within the quadrangles mapped oil and gas have been found both 
in the Santa Barbara-Ventura Basin and in the Santa Maria Basin. The 
former jdelds high-gravity oil and considerable gas from sands of the 
Vaqueros, Sespe, and Eocene formations in closed structures along the 
southern coastal area between Capitan and Point Conception. The latter 
basin yields low-gravity oil from fractured siliceous shale of the Monterey 
formation in closed structures in the Purisima Hills and San Rafael 

The intermediate areas between the two stratigraphic basins, namely 
the coast north of Point Conception, Santa Ynez Mountains, Santa Rita 
Hills, Burton Mesa, Lompoc and Santa Ynez Valleys, and southeastern 
Purisima Hills have failed to yield oil or gas. Throughout these areas are 
many closed anticlines exposing Monterey shale at the surface. Wells 
have been drilled on nearly all of these structures to test the lower Mon- 
trey shale and the underlying lower ^Miocene or Eocene sands, but all 
were dry holes, generally without showings. The results of exploratory 
wells drilled throughout these areas are indicated in the accompanying 
tables (see pp. 70-74). 

Santa Barbara-Ventura Basin 

Capifan Oil Field. The subsurface structure of the Capitan oil field 
is an anticlinal dome closed by drag against the north-dipping Erburu 
fault. This structure is not apparent on the surface, as the Erburu fault, 
which in part limits production on the north, crops out through the 
southern portion of the field and is paralleled on the north by a syncline 
in Mouterej' shale. 

Since its discovery in 1929 the Capitan field has produced more 
than 11,000,000 barrels of 16° to 43° gravity oil from an area of 296 
acres. Oil is produced from the Vaqueros sandstone at a depth of from 
1000 to 1400 feet below sea level, and also from two zones in the upper 
Sespe : the Erburu 8 zone and Erburu 10 zone. The upper Sespe also 
contains a gas zone. Deeper drilling since 1945 has resulted in the dis- 
covery of large flowing wells, from the Covarrubias zone of the lower 
Sespe, and the Eocene zone at the top of the Gaviota-Sacate ("Cold- 
water") formation, which have greatly augmented the reserves of this 

The Vaqueros zone was discovered by General Petroleum Corpora- 
tion's No. "Erburu" 1 well in 1929. The Vaqueros sand produces from 
100 to 600 barrels per day of 20° A.P.I, gravity oil. 

The Erburu 8 zone of the upper Sespe was discovered by General 
Petroleum Corporation's Xo. "Erburu" 8 well, completed in January 
1931 for 250 barrels per day of 40" to 42° gravity oil. This sand is 125 
feet thick, is topped at 660 feet below the top of the Sespe, and produces 
125 to 1000 barrels per day of oil. The Erburu 10 zone is 75 feet thick, is 
topped at 1000 feet below the top of the Sespe, and produces 100 to 600 
barrels per day of 44° gravity oil. 

The Covarrubias zone was discovered by Shell Oil Company's No. 
"Covarrubias" 1-35, completed February 1945 flowing 1375 barrels per 
day of 39° gravity oil from the interval 3355-3637 feet in the lower Sespe. 


The Eocene or "Coldwater" zone was discovered by Shell Oil Com- 
pany's No. " Covarrubias " 1-36, completed August 1945 flowing 520 
barrels per day of 39° gravity oil from the interval 3805-3825 feet from 
uppermost marine Oligocene-Eocene (Gaviota or "Coldwater") sand- 

As of January 1, 1948, Capitan field had 66 producing wells, of 

which 8 were flowing, 57 pumping, and 1 shut in. Cumulative production 

to that date was 11,897,000 barrels. 

The geology of Capitan field is described in detail b}^ Dolman ^^ and 

Befugio Cove Area. At the mouth of Refugio Canyon is a large 
closed anticline in Monterey shale. Rincon shale is exposed on the crest 
of the fold at Refugio Cove. The first test well. Shell Oil Company No. 
"Rutherford" 1, drilled in 1928, found both Vaqueros and Sespe sands 
devoid of oil, and was drilled far into the Gaviota-Sacate (" Coldwater") 
formation which flowed dry gas and sulfur water. Since the deep test 
many other wells have been drilled on this closed structure, but none has 
obtained commercial production except Rothschild Oil Company No. 
"Orella" 1 which discovered the small Refugio gas field. 

Befugio Gas Field. The Refugio gas field occurs on a small closed 
anticline in Monterey shale within the Refugio dome about a mile west 
of Capitan field. The discovery well, Rothschild No. "Orella" 1, drilled 
in 1946, flowed at an estimated rate of 5.000.000 cubic feet of gas per day 
from the Vaqueros sandstone at about 2500 feet. To date this field con- 
tains three gas wells. 

Drake Area. Near Drake station, at the mouth of Caiiada Santa 
Anita, is a syncline on shore and a supposed anticline off shore in Sisquoc 
shale with axial planes hading northward. The first test well, Western 
Gulf No. "Hollister" 1, drilled in 1928, drilled into the Vaqueros sand- 
stone at 3088 feet and blew in out of control, producing an estimated rate 
of 25,000,000 cubic feet of gas per day. After the well Avas brought under 
control, it produced a few barrels of light oil and considerable salt water. 
The gas flow soon died down and after all attempts to shut off the water 
failed, the well was abandoned. Several other test wells were drilled on 
this structure, but all failed to obtain commercial production. 

Point Conception Area. The north-dipping homocline in the Point 
Conception area is the possible north flank of a large off-shore anticline. 
This structure was tested in 1930 by Standard Oil Company No. ' ' Ger- 
ber" 1 at Government Point. This well found some gas and salt water in 
the Vaqueros sandstone, was drilled through the Alegria, Gaviota, and 
Sacate formations and encountered good shows of light oil in tight sands 
of the Sacate ( ? ) . After all tests failed to obtain production, the well was 

Santa Maria Basin 

Lompoc Field. Union Oil Company, which discovered Lompoc field 
in 1903, controls the major part of it and developed it in a conservative 
way until 1940. As of that date, the field produced 7,900,000 barrels of oil 
from 49 wells from an area of about 2200 acres. However, since 1942 this 
field has undergone renewed and more thorough development, due to 

B2 Dolman, S. G., Capitan oil field : California Div. Oil and Gas, Summary of Opera- 
tions, California Oil Fields, Kept. 24, no. 2, pp. 15-26, 1938. 

63Kribbs, G. R., Capitan oil field: California Div. Mines Bull. 118, pp. 374-376, 


heavy demand for oil since the last war. Wells have been drilled at the 
rate of about two per month. The new wells completed have greatly 
increased production of the field, but the acreage has not been appreci- 
ably extended, as outpost wells are structurally too low and fail to obtain 
production. The field has produced 14,601,000 barrels of oil to January 1, 
1948. On that date, production was from 77 wells, of which 6 were flow- 
ing, 67 pumping, and 4 shut in. 

Lompoc field produces 15° to 24° A.P.I, gravity oil from fractured 
siliceous (only slightly cherty) shale of the upper Monterey, at depths 
from 1900 to 2200 feet below sea level. Production is from the western 
Purisima anticline which is closed and made up of at least two closed 
anticlines en echelon, separated by a syncline which is probably faulted 
near the axis. The geology of Lompoc field has been described in detail 
by Dolman ^* and Dibblee.^° 

Purisima Hills. Many test wells have been drilled throughout the 
Purisima Hills but with the exception of Lompoc field no commercial 
production has been obtained. Wells drilled in the central portion of the 
Purisima Hills were dry holes, as the structure of this portion is a saddle 
in the Purisima anticline. The eastern portion contains several closed 
anticlines exposing Monterey shale ; these were tested, but the Monterey 
is here underlain by Espada or Franciscan and no oil was found. The 
south flank was tested by Richfield Oil Corporation No. ' ' Skytt" 1 drilled 
to 6007 feet and abandoned without showings. 

Wells drilled on the north flank of the Purisima Hills found the 
Sisquoc too thick to penetrate, although the Monterey was reached on an 
anticline across Santa Ynez Canyon where some heavy oil was found in 
Whittier Associates No. "Barham" 1. This well produced about 78 bar- 
rels of oil per day from fractured cherty shale of the Monterey at 4000 
feet. No. "Barham" 2 was a dry hole, but No. "Barham" 3 obtained 
small production. These wells are not commercially productive. 

Zaca Field. The discovery of Zaea oil field was made in 1942 by 
Tidewater Associated Oil Company, when its No. ''Davis" 1 well was 
brought in pumping 294 barrels of 7° gravity oil including 37 barrels 
of distillate, 33 percent emulsion from Monterey cherty shale, at 4465 
to 5956 feet. The well settled to 150 barrels per day, 7° gravity clean oil. 
Tidewater Associated Oil Company, which controls the field, has been 
developing it in an orderly way and to date has 10 producing wells. The 
field produces a moderate amount of oil averaging 8° gravity, which is 
so viscous that distillate must be injected in order to render the tarry 
oil fluid enough to pump out. As of January 1, 1948, Zaca field had pro- 
duced a cumulative total of 358,000 barrels of 8° to 10° A.P.I, gravity oil 
from these wells. 

The structure of Zaca field is a large closed anticline in the Sisquoc 
and overlying formations, and the oil is produced from fractured cherty 
shale of the Monterey which here unconformably underlies the Sisquoc. 
Detailed structure of the Monterey is not known, but is regionally a 
homocline dipping southwest, and the oil occurs in the cherty shale where 
it is overlapped by the Sisquoc. 

"Dolman, S. G., Lompoc oil field, Santa Barbara County, California: California 
Div. Oil and Gas, Summary of Operations, California Oil Fields, Rept. 17, no. 4, pp. 
13-19, 1932. 

» Op. cit 



[Bull. 150 



















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Four deposits of asphalt in the form of tar-impresmated sands occur 
in the area mapped, one on the south coast and three in the Purisima 
Hills. None has been quarried. 

Along: the sea-cliff within 1^ miles west of Gaviota Beach are five 
exposures of chert pebble eonelomerate and sand ; and one exposure on the 
south face of a hill 2 miles west, in which the sand is well impregnated with 
asplwilt. This conglomerate probably form.s the base of the Sisquoc 
although some occurs in the upper ^lonterey. It attains a maximum 
exposed thickness of about 50 feet and dips about 45° S. Thin lenses of 
this conglomerate also crop out east of Cuarta Canyon and at Sacate 

In the eastern Purisima Hills is a large deposit of tar-soaked sand 
at the base of the Sisquoc on the west .side of the canyon 1^ miles north 
of Jonata Park. ThLs deposit consists of very fine sand heavily impreg- 
nated with asphalt. It is about 75 feet in maximum thickness and extends 
about a mile, dipping steeply north into a syncline. This tar sand grades 
laterally along the strike into oil shale. 

Redrock ^Mountain in the central Purisima Hills is formed by a 
large depo.sit of tar-soaked sand. This consists of fine sand of the Careaga 
formation, is about 50 feet thick, and caps the mountain. The sand is 
well impregnated with asphalt. Two erosional remnants of this tar sand 
occur about 1 mile down the spur to the southwest. The tar sand of 
Redroek Mountain is underlain by highly bituminous shale of the lower 
Sisquoc which has locally been burned, causing it to become brilliant 
red and locally scoriaceous. 

A small deposit of tar sand occurs at Lompoc oil field in Purisima 
Canyon. This consists of medium-grained Careaga sand impregnated 
with asphalt. It is about 25 feet thick and dips gently south. At the 
south end of Harris grade is exposed about 15 feet of basal Careaga (?) 
tar sand lying uneonformably on Sisquoc diatomite. 


The southern portion of the Santa 'MariR Basin is noteworthy for 
its extensive deposits of diatomite. or diatomaceous earth. This is all of 
marine origin, of upper Miocene and lower Pliocene age. and is confined 
largely to the Sisquoc formation, except for local interbeds in the upper 
Monterey shale. The diatomite deposits are developed in the Purisima 
Hills. Santa Yuez Valley, and in the northern foothills of the Santa Ynez 
^Mountains south of Lompoc Valley. In the last-named area it is remark- 
ably pure and makes up the largest known diatomite deposit of com- 
mercial value in the world, which contains the world 's largest diatomite 
workings. Diatomite deposits of known and potential economic value 
are shown on the economic maps. 

Types of Diatomite 

The diatomite of the Sisquoc and ]\Ionterey formations is of three 
types: (1) pure thinly stratified: (2) impure coarsely stratified; and 
(3) impure massive. The pure thinly stratified diatomite is of commercial 
value and is marketed under the trade name "Celite." by Johns-Man- 
ville Products Corporation. The impure diatomites are of little or no 
commercial value. 


The thinly stratified diatomite is soft, very light weight, porous, and 
made up of laminae averaging about gV of an inch. It is coherent, but 
tends to fracture along bedding planes, and is nearly pure white when 
dry ; but below the .surface it is cream-colored and contains 50 percent 
moisture. It is of such high porosity that it will absorb nearly 75 percent 
water Avhen saturated. The material is made up almost entirely of well- 
preserved siliceous tests of diatoms. These comprise more than 200 spe- 
cies, but in general there are two types — disc-shaped diatoms, and fili- 
form or needle-shaped diatoms. These occur in varying ratios in different 
strata, but the disc types generally predominate. In addition to diatoms, 
there are subordinate siliceous remains of animal life svich as radiolaria, 
silicoflagellates, and sponge spicules. The thinly stratified diatomite 
contains verj^ minor impurities such as flakes of volcanic ash and par- 
ticles of clay, quartz, or amorphous silica. 

The impure coarsely stratified diatomite consists of the above type 
with as much as 10 percent admixture of clayey material. This diato- 
mite differs from the thinly stratified type ; it is heavier and less porous, 
and is cream colored when dry, and light brown when moist. The diatoms 
are generally more broken. This type is rejected as waste. 

The impure massive diatomite is also cream colored and contains 
an admixture of clayey material ranging from a fraction of 1 percent 
to 50 percent, beyond which it grades into diatomaceous claystone. It is 
typically massive and breaks with conchoidal fracture. The diatoms are 
generally broken and poorly preserved, and the material is somewhat 
harder and less porous than the other two types. 

Deposits South of Lompoc Valley 

The hills south of Lompoc Valley and the western Santa Rita Hills 
contain several deposits of high-grade commercial diatomite covering an 
area of about 17 square miles. This diatomite is of upper Miocene age 
and comprises the lower 1000 feet of the Sisquoc formation (assigned to 
Monterey formation by Arnold and Anderson,^*^ and by Mulryan ^'^) , and 
minor amounts are locally interbedded in the siliceous shale of the upper 
Monterey formation. The upper Sisquoc in this area is of the impure 
massive type and consequently of no economic value. The high-grade 
lower Sisquoc diatomite crops out along the northern slopes of the Lompoc 
and Santa Rita Hills, where it dips northward under Lompoc Valley. 
Farther south in these hills the diatomite is largely eroded away, but is 
preserved in several basin-like synclines where it is quarried. 

The lower Sisquoc diatomite consists of alternating laj^ers of the 
pure thinly stratified variety, and the impure coarsely stratified variety, 
as previously described. Determination of the quality of the diatomite 
requires much sampling and microscopic examination. Chemical tests 
are required to determine the amount and kind of impurities. As the pure 
diatomite occurs in certain strata, selective quarrying of these layers is 
required. The lower Sisquoc diatomite is remarkably free of other rock 
types. Layers of opaline chert seldom occur and these in beds only a few 
inches thick. In some places the chert occurs as nodules or nodular layers. 
Thin layers of volcanic ash are locally present. In the Santa Rita Hills the 
base of the lower Sisquoc diatomite is locally marked by a layer of phos- 
phatic pebbles or pellets, or by sand. At some places about a foot of lime- 

^ Op. cit. 

^■^ Mulryan, H., Geology, mining', and processing of diatomite at Lompoc, Santa 
Barbara County, California : California Div. Mines Rept. 32, pp. 133-166, 1936. 


stone occurs near the base, bnt in most places the lower Sisqiioc diatomite 
lies conformably on ]\Ionterey clierty shale, or grades down into it through 
about 50 feet of beds. 

Diatomite of the upper Monterey is similar to that of the lower 
Sisquoc, except that it is interbedded with opaline and cherty shales. 
Much of the diatomite is of high quality, but it seldom occurs in pure 
beds more than 50 feet thick. The diatomites of the upper Monterey are 
local phases of opaline cherty shale, into which they grade laterally. They 
occur in the vicinity of Salsipuedes and San Miguelito Canyons, and also 
in Espada Canyon. 

Deposits of Purisima Hills and Santa Ynez Valley 

The Sisquoc formation of the Purisima Hills is composed largely of 
impure, coarsely stratified and massive diatomite, and is therefore of 
little or no commercial value. However, in the eastern Purisima Hills 
west of Zaca Creek, there is a small deposit of high-grade diatomite, con- 
sisting of about 500 feet of thinly stratified diatomite in the uppermost 
Monterey formation below the basal Sisquoc tar sand. This diatomite 
occurs in a west-plunging syncline 1 mile north of Jonata Park, and also 
on the north flank of the adjacent anticline to the north. The lower 
Sisquoc also contains some thinly stratified diatomite 1 mile west of 
Jonata Park. None of these deposits have been worked. 

In Santa Ynez A'alley in the vicinity of Solvang is a small deposit of 
pure thinly stratified diatomite occurring in the lower Sisquoc formation. 
About 500 feet of diatomite is exposed and occurs in a sharp anticline 
and s^aicline. The deposit was quarried and mined 1 mile northwest of 

On the north flank of the anticline east of Santa Ynez are several 
outcrops of stratified white diatomite about 1000 feet thick in the lower 
Sisquoc formation. Some of this is of possible commercial grade. It is 
largely concealed by terrace deposits. 

Uses of Diatomite 

To quote from ]\Iulryan ^^ : 

"Briefly summarizing-, the principal uses of Celite Diatomite Prod- 
ucts are: In insulation at comparatively high temperatures, also low tem- 
peratures, building insulation, and filtration of all types of liquids from the 
most viscous to the least viscous ; as admixtures and mineral fillers where 
a chemically inert light-weight mineral is required, as a mild abrasive in 
polishes, and a filler in paints." 

Diatomite Quarries 

Johns-ManviUc Qiiarrics. For a detailed description of the Johns- 
Manville quarries, the reader is referred to Mulryan 's ^^ report in which 
the geology of the diatomite deposit and the mining and processing 
operations by the Johns-Manville Products Corporation are described. 
These are summarized in the following abstract ^^ : 

"The largest and purest known deposit of diatomite is being actively 

mined and processed three and one-half miles south of Lompoc, Santa 

Barbara County. California, by the Johns-Manville Corporation. 

"The workings cover 4000 acres, the depth of economically recoverable 

diatomite being 1000 feet. 

58 0p. cit., p. 164. 

59 Op. cit, pp. 133-136. 

80 Mulryan, H., op. cit., pp. 133-134. 


"These marine beds assigned to the Monterey formation, upper 
Mioocne are generally soft, white, extremely porous, light weight, and of 
remarkable uniformity and purity. 

"The diatomite is quarried on the surface by gasoline and diesel- 
powered shovels, and loaded into trucks which haul the material to vertical 
storage shafts sunk in the diatomite. The diatomite is drawn off at the 
bottoms of the holes into cars and hauled underground by electric trolley 
locomotive to the jirimary crushing plant. 

"The crushed crude is conveyed to mill bins and processed. Powders 
for filtration, admixtures, mineral fillers, and insulation purposes are pro- 
duced in the milling systems. 

"Insulation brick are sawed directly in the quarries or produced from 
aggregates and calcined in a tunnel or beehive kiln. 

"The company maintains a complete machine shop, garage, electric 
and carpenter shop, camp for employees, hospital, and a plant development 
department at the deposit. A research staff is establislied at Manville, New 

Concerning the diatomite deposit, Mulryan ^^ makes the following 
statement : 

"The company owns or controls an area comprising 4000 acres in the 
main deposit. The diatomite contained therein is remarkable because of 
its high degree of purity in this huge deposit. It is generally accepted as the 
largest and purest known deposit in the world. Its great thickness, more 
than 1000 feet, and its undisturbed condition, with the added benefit of 
sufficient relief to permit easy mining conditions, certainly place the deposit 
in a unique position." 

The writer is not in complete agreement with Mulryan concerning 
the geology of the diatomite deposit. Mulryan follows Arnold and Ander- 
son ^^ in assigning the diatomite to tlie Monterey formation, but the 
writer restricts only the diatomite interbedded with siliceous shales to 
the Monterey, and assigns the overlying 1000 feet of homogeneous dia- 
tomite to the Sisquoc formation, on the basis of regional mapping and for 
reasons stated under Stratigraphy . 

Mulryan ""^ states that the eastward-trending syncline containing 
the diatomite deposit of Johns-Manville Products Corporation is a down- 
faulted block, bounded on the northeast by a major cross-fault following 
Salsipuedes Creek, and on the southwest by another in San Miguel 
Canyon. The writer has found no conclusive evidence of such faults — at 
least not on a major scale — and believes that the synclinal structure con- 
taining the diatomite rises both east and west from the Johns-Manville 
propert}^ forming a structural basin as indicated on the geologic map of 
the Lompoc quadrangle. 

Dicalitc Quarries. About 7 miles southeast of Lompoc is a large dia- 
tomite deposit on the portion of Rancho San Julian owned by W. C. H. 
Dibblee. This deposit was leased in 1942 to the Dicalite Company which, 
since 1945, has been the Dicalite Division of Great Lakes Carbon Cor- 
poration. The diatomite of this deposit is of high commercial value similar 
to that of the Johns-Manville quarries; it covers some 1,500 acres and 
contains an estimated 166,000,000 cubic yards of diatomite. 

The diatomite of the Dicalite quarries is assigned to the lower Sis- 
quoc formation and is the same in lithology and quality as that of the 
Johns-Manville quarries ; it lies with sharp, but conformable, contact on 
Monterey cherty shale. The diatomite occurs in a structural basin, 

■ - ■ ■ - • 

6iOp. cit.p. 141. 

82 Op. cit. 

esQp. cit., p. 139. 


similar to that of the Jolms-Manville deposit, composed of three syiiclines 
separated by two anticlines. These folds trend about N. 85° W. and extend 
abont 2 miles; dips vary from flat on the axes of the folds to 50° on the 
flanks. The north vSyncline is the largest and contains diatomite to an 
estimated maximum depth of 700 feet. The middle syncline contains dia- 
tomite to about 500 feet maximum depth, and the south syncline to about 
250 feet depth. 

The diatomite of the Dicalite quarries contains occasional thin layers 
of volcanic ash as at the Johns-Manville quarries. Some diatomite layers 
carry many dark brown phosphatic lenticular concretions 1 inch to 2 
inches in diameter and half an inch thick. 

In 1943 the diatomite deposit w^as quarried by the Dicalite Company, 
and in 1947 bj' Dicalite Division of Great Lakes Carbon Corporation. 
The method used was surface quarrying and hauling by truck. Operations 
at the deposit are still in the development stage, there being no under- 
ground workings nor processing plant. The deposit has been prospected by 
trenching and scraping of ridges by bulldozer, and by vertical holes 30 
inches in diameter and about 50 feet deep. 

Quarrying operations have been confined to the north syncline. Only 
layers containing thinly stratified pure diatomite are quarried; asso- 
ciated impure diatomite is dumped as overburden. In 1943 the high- 
grade diatomite was quarried by power shovel, but during 1947 it was 
quarried by carry-all. The quarried material is loaded onto dump trucks 
which haul it to stock piles located adjacent to the main surfaced road. 
From the stock piles the diatomite is moved by dragline to a loading chute 
where it is loaded onto truck and trailer, covered by tarpaulin, and 
hauled about 150 miles to the Dicalite processing plant located at Wal- 
teria in the Palos Verdes Hills east of Palos Verdes, California. 

Diatomite Quarry in La Salle Canyon. Five miles southwest of 
Lompoc on the east side of La Salle Canyon, lower Sisquoc diatomite dips 
steeply north. The plant is idle. 

Diatomite Quarry Near Solvang. One and a half miles northwest 
of Solvang lower Sisquoc diatomite dips generally south, but a small fold 
is exposed. The plant is idle. 


Deposits of limestone occur at the base of the Monterey shale in the 
northwestern Santa Ynez Mountains near Lompoc. Limestone crops out 
on both sides of El Jaro Canyon below the juncture of Los Amoles Creek. 
The limestone here is white, but weathers gray on the surface ; it is dense, 
massive, and hard, but generally much fractured, breaking into irregular 
pieces. The upper portion is limestone but the lower portion becomes 
calcareous tuffaceous sandstone with local occurrences of conglomerate 
at the base. Total maximum thickness aggregates about 150 feet; the 
pure limestone has a maximum thickness of about 70 feet. Locally several 
thin lenses of limestone occur in the overlying shales of the Monterey. 
The structure of the limestone and overlying shales here is that of gently 
undulating folds. The limestone forms many landslides, especially where 
it is underlain by soft formations. 

Between San Pascual and La Salle Canj^ons southwest of Lompoc 
is a limestone bed of about 100 feet maximum thickness which dips 
steeply north and is exposed for a distance of more than 2 miles, between 


Monterey shale above and Tranquillon agglomerate below. The limestone 
is similar to that of El Jaro Canyon, consisting of pure limestone grading 
downward into calcareons sandstone. 

The Miocene limestone of the northwestern Santa Ynez Mountains 
has not been worked for cement, but at El Jaro Creek, 7 miles southeast 
of Lompoc, it has been quarried and crushed for road gravel. 

Southwest of Solvang the basal Monterey limestone is exposed along 
the south bank of the Santa Ynez River for a distance of about three- 
quarters of a mile, Avhere it dips steeply north. The limestone here is 
impure and is made up largely of calcareous algae. It is quarried for road 

The Sierra Blanca limestone exposed in Nojoqui Canyon and at 
several other localities in the Santa Ynez Mountains, is sandy and con- 
tains calcareous algae. It was quarried at Nojoqui Canyon for road 


Thin beds of bentonite are locally developed at the base of the Mon- 
terey shale or in the Tranquillon formation at various places in the Santa 
Ynez Mountains. Several exposures occur between Gaviota and Cojo 
Canyon on the south flank ; it is also exposed in Gijote Canyon and Llani- 
tos Canyon. It is probably rhyolitic, as it is associated with rhyolite tuff 
in Cojo Canyon. It has not been quarried. 


Slab-rock suitable for flagstone has been quarried at two locations 
in the western Santa Ynez Mountains. One of these is at the Golondrina 
Dairy of Ranclio San Julian, on the highway 6 miles west of Las Cruces. 
The rock was hand-quarried in 1929 by A. Dibblee Poett and sold to 
private individuals. The rock-slabs occur in shale of the upper part of the 
Sacate formation (Eocene) which here dips steeply north on a north- 
facing hillside. The slabs average about 3 inches thick, are unusually 
large, and consist of extremely hard, coherent, fine-grained sandstone. 
They make excellent flagstones for garden-paths, steps, or stone floors. 

The flagstones are confined to the upper shale member of the Sacate 
formation, and are well developed along the strike some 2 miles to the 
west on the divide between San Julian and Los Amoles Valleys, where 
they dip gently northeast. 

Flagstones were quarried at Tajiguas prior to 1942. These occur as 
large slabs of hard, coherent calcareous and siliceous shale in the lower 
Monterey shale, ranging up to a foot in thickness. The formation here 
dips about 20° S., and is almost a dip-slope on a south-sloping hillside. 

Road Gravel 

Dihhlee Quarry. The Dibblee quarry is a large quarry on the north 
side of El Jaro Canyon 7 miles southeast of Lompoc. It is on the W. C. H. 
Dibblee property of Rancho San Julian and was worked occasionally 
from 1928 to 1944 by the Santa Barbara County Road Department. The 
rock quarried is basal limestone of the Monterey shale, which here dips 
north into the hill. The limestone here is about 40 feet thick, grading 
upward into brittle cherty shales. About 15 feet of conglomerate occurs 
at the base of the limestone. The limestone and overlying shale are much 
fractured. Quarrying is done by blasting and power shovel, and the rock 


is crushed into gravel of various sizes. It was used for surfacing the 
Lompoc-Las Cruces road and other roads in the Lompoc area. 

Alisal Quarry. The Alisal quarry is located on the south side of 
Santa Ynez River 1 mile south of Solvang. The quarry is in basal lime- 
stone of the ^lonterey shale, vrliich here dips very steeply north and forms 
the south bank of the Santa Ynez River. The rock consists largely of very 
hard light-gray algal limestone, about 50 feet thick. The basal portion 
consists of calcareous and tuffaceous pebbly fossiliferous hard sandstone. 

The quarri- was operated at various times by the county- between 
1926 and 1941. by blasting and power shovel. The rock was crushed into 
gravel of various sizes and used in surfacing roads in the Santa Ynez 

CaU(jon Quarry. The Callejon quarry is near Callejon Dairy of 
Rancho Sau Julian, on the Lompoc-Las Cruces road. 4 miles west of 
Las Cruces. The rock was first quarried in 1928 by the Santa Barbara 
County Road Department, and again iu 1947-48 by the California Divi- 
aon of Highways through X. TV. Ball and Son. contractor. The quarry is 
in Taqueros conglomerate and sandstone which here is on end or slightly 
overturned northward. The formation is about 300 feet thick. The rock 
consists of basal pebble conglomerate with a brown clayey sandstone 
matrix, grading upward into pebbly sandstone. The formation is soft and 
easily quarried by bulldozer and power shovel. About 67.000 tons were 
removed in 1947-48 and the material was used in resurfacing the highway 
between Las Cruces and San Julian ranch-house gate. 

Monterey Shale Gravel Quarries. Loose talus gravel of Monterey 
cherty shale has been quarried at many places in the vicinity of El Jaro 
Creek for use as road gravel. One of these is on the east side of El Jaro 
Canyon 7^ miles southeast of Lompoc : another in Los A moles Canyon 
half a mile above the junctiu-e with El Jaro Creek: one at El Chorro 
Ranch, 9 miles southeast of Lompoc : and one about a mile up Yridises 

All of these were quarried in 1928-30 by the Santa Barbara County 
Road Department for use on the Lompoc-Las Cruces highway which was 
being rebuilt at that time. Quarrying was done by steam shovel, and the 
loose shale was loaded directly into trucks without treatment. 

Buell Flat Bock Quarry. Just west of Solvang, Recent stream 
gravel of the Santa Ynez River bed is quarried by the Buell Flat 
Rock Company of Solvang. and is used mainly as road material. The 
gravel is fairly clean and is quarried by power shovel, and sorted by 
screening into various sizes from 2-inch to pea gravel. 

Biver Quarry Xear Santa Bosa Pari-. Jn the Santa Ynez River bed 
at the mouth of Drum Canyon near Santa Rosa County Park is a gravel 
quarry operated by Cox and Chilson of Lompoc. The gravel is similar 
to that of Buell Flat quarry and operations are the same. 

Manganese Ore 

A small deposit of manganese ore (pyrolusite or psilomelane) occurs 
in the Franciscan formation of the San Rafael ^Mountains 7 miles north- 
east of Los Olivos. The ore occurs as a somewhat lenticular mass roughly 
20 feet thick in dark maroon ferruginous chert, dipping steeply north. 
"Workings consist of an open shaft about 6 feet square and about 20 feet 
deep. The prospect may contain a lower level but was not entered. 



This and another manganese prospect of little apparent value were 
briefly described by F, S. Hudson as Santa Barbara County nian<?anese 
deposit no. 2, La Laguna Rancho, in a recent bulletin by Trask and 


Springs. In Santa Ynez Valley, immediately west of Santa Ynez, 
a large artesian spring issues from terrestrial gravels. The volume is 
sufficient for irrigation and was used for this purpose on the lands of 
Mission- Santa Inez by the Franciscan Fathers who first settled in Santa 
Ynez Valley. 

The Santa Ynez spring is believed to issue from the saddle between 
the east end of the Purisima anticlinal uplift and the large anticline 
rising eastward from Santa Ynez. This gravel-filled gap between these 
two uplifts apparently acts as the outlet for the underground water of 
practically the entire drainage basin of upper Santa Ynez Valley, and at 
this outlet the water gathers in such large volume as to reach the surface. 

In the San Rafael Mountains numerous springs issue from serpen- 
tine and landslide masses of the Franciscan formation. In the Santa Ynez 
Mountains are many springs, which issue mainly from the following 
formations in order of abundance : ( 1 ) Vaqueros pebble conglomerate ; 
(2) Sespe conglomerate (Nojoqui-Alisal area) ; (3) Tranquillon vol- 
canics and Monterey basal limestone ; (4) Matilija sandstone ; (5) sand- 
stones of other formations; (6) Monterey cherty shale; and (7) clay 
shales. In general, springs are most abundant in these formations where 
the geologic structure is complex and where there is much landsliding. 

One of several hot springs which issue from the Santa Ynez fault 
occurs within the mapped area just south of Las Cruces. This spring is 
apparently of deep-seated origin along the fault. The water has a tem- 
perature of about 100° F., and carries some sulfur. 

Few springs occur in the Purisima and San Rafael foothills. 

Ground Water. A detailed investigation of the ground-water 
resources of Santa Ynez and Lompoe Valleys has recently been completed 
by J. E. Upson and others.^^ In Lompoe Plain and throughout the flood- 
plain of the Santa Ynez River, wells drilled into the basal gravel member 
of the alluvium produce water in large amounts sufficient for irrigation. 
The Careaga sand which underlies this gravel in Lompoe Plain is likewise 
M^ater-bearing, but the loose sand runs into the wells and causes trouble. 
Irrigation water is also produced from wells drilled into alluvial gravels 
of stream valleys traversing the San Rafael foothills and upper Santa 
Ynez Valley. Alluvial sands and gravels of Los Alamos Valley also yield 
large amounts of water. 

The alluvium of stream valleys within the Santa Ynez Mountains 
and Purisima Hills generally contains too much loam and too little gravel 
to produce enough water for irrigation, but generally yields enough for 
stock or domestic purposes. 

Wells drilled into gravels of the Paso Robles formation yield small 
amounts of water. The Careaga sand yields fair amounts, but generally 
causes sanding trouble. Diatomite, shale, and siltstone formations do not 
yield water unless fractured. Brittle, fractured Monterey cherty shale 

•" Trask, Parker D., and others, Geologic description of the manganese deposits of 
California: California Div. Mines Bull. 125, p. 173, 1943. 
«5 0p. cit,1947. 


will generally yield water — sometimes in fair quantities. Sandstone gen- 
erally yields small amounts, but when the formation is tight, the water 
comes mainly from fractures or joints rather than from the sandstone 
itself. Under favorable structural and topographic conditions fair 
amounts of water can be obtained from sandstones. J. S. HoUister has 
drilled several near-horizontal wells into steeply dipping Matilija sand- 
stone on the Hollister and San Julian ranches and has obtained up to 120 
gallons per minute of excellent water. 

Water from some formations locallj' contains large amounts of 
mineral salts. This is especially true of waters from serpentine, or from 
the Sespe, Vaqueros, and Monterey formations, which locally contain 
hj'drogen sulfide, sulfate, and carbonates of calcium, magnesium, iron, 
sodium, and potassium, 


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Upson, J. E., Thomasson, H. G. Jr., and others. Geology and water resources 
of Santa Ynez river valley, Santa Barbara County, California : U. S. Geol. Survey 
Duplicatetl Rept., pp. 1-322, June 1947. 

Woodring, W. P., Upper Eocene orbitoid foraminifera from the western Santa 
Ynez Range, California, and their stratigraphie significance: San Diego Soc. Nat. 
Hist. Trans., vol. 6, no. 4, pp. 14.5-170, 1930. 

Woodring, W. P., Bramlette, M. N., Lohman, K. E., and Bryson, R. P., Geologic 
map of Santa Maria district, Sant^i Barbara County, California : U. S. Geol. Survey 
Oil and Gas Investigations, Prelim. Map 14 (in six sheets), 1944. 

Woodring, W. P., Bramlette, M. N., and Lohman, K. E., Stratigraphy and pale- 
ontology of the Santa Maria district. California : Am. Assoc. Petroleum Geologists 
Bull., vol. 27, no. 10, pp. 1335-1360, 1943. 

Woodring, W. P., Loofbourow, J. S. Jr., and Bramlette, M. N., Geology of Santa 
Rosa Hills, eastern Purisima Hills district, Santa Barbara County, California : U. S. 
Geol. Survey Oil and Gas Investigations, Prelim. Map 26, 1945. 



Agua Caliente Canyon region : Alegria formation in, 30 ; faulting in, 55 

Alegria Canyon region : Alegria formation in, 30 ; Monterey sediments, tar-soaked, 
pi. 17 ; Monterey shale in, pi. ISB, pi. 14, pi. 15A ; Santa Ynez fault in, 55 ; 
terrace deposits in, 50 ; Vaqueros formation in, 32 

Alegria formation, 29, 30-31, 32, pi. IIB, 38, 49, 62, 68 ; marine facies of Sespe forma- 
tion, 30-31 

Algae, calcareous, from Monterey limestone, 40, 80 

Alisal Canyon : Espada formation in, 22 ; Rincon claystone in, 33 

Alisal Canyon region, Vaqueros formation in, 32 

Alisal gravel quarry, 81 

Alisal-Nojoqui area : see Nojoqui- Alisal area 

Alisal ranch region, faulting in, 57 

Alluvium, Recent, 38, 39, 48, 50-51 

Amoles Creek region: Tranquillon volcanics (?) in, 34; see also Los Amoles region 

Anita shale, 23, 24, 25, 26, 27, pi. lOJ^, 38, 49, 01, 62; Sierra Blanca limestone lens 
in, 25 

Anticlinal structures : see Structure, 51-60 

Arroyo Hondo region : Alegria formation in, 31 ; Gaviota formation in, 31 ; Vaqueros 
formation in, 32 

Artesian water : see Springs 

Asphalt, 75; tar-soaked sediments, Monterey, pi. 17; tar-soaked sediments, Sisquoc, 

Astrodapsis antiselli zone, 48 

Astrodapsis hreweriantis zone, 48 

Astrodapsis peltoides zone, 48 

"Aucella" crassicollis zone, 49 

''Aucella" piochii zone, 49 

Baculites chicoensis zone, 49 
Baggina californica zone, 42 
Ball & Son, N.W., 81 
Basement : see Franciscan 

Bentonite, 80; in Monterey shale, 40 ; in Tranquillon volcanics, 34, 36, 38 
Birbent Canyon, Sisquoc formation in, 44, 46 

Birbent Canyon region : Careaga formation in, 45, 46 ; structure, 60 
Bixby Canyon, Tranquillon volcanics in, 34 
Bixby Canyon region, Vaqueros formation in, 31 
Boliviiia h iighesi zone, 42 
Briones moUuscan stage, 48 
Buell Flat gravel quarry, 81 
Buell Flat Rock Company, 81 

Buellton region, pi. \2B ; unconformity in, pi. 12A 
Bulito Canyon : Alegria formation in, 31 ; see also El Bulito Canyon 
Bulito Canyon region : faulting in, 56 ; Gaviota formation in, 29 
Bulito fault, 56 
Burton Mesa : Franciscan formation in, 21, 62 ; Lospe formation in, 33 ; Monterey 

shale in, 37; petroleum exploration in, 67; physiography, 19; Sisquoc formation 

in, 43, 64 ; structure, 51, 58, 65 
Burton Mesa region, Orcutt formation in, 50 


Cabrillo, exploration of Santa Barbara coast by, 9 

California Division of Highways, 81 

Callejon gravel quarry, 81 

Canada de la Vina region, Monterey shale in, 35 

Canada de Santa Anita : Gaviota formation type locality, 29 ; petroleum exploration 

at mouth of, 68 ; see also Santa Anita Canyon 
Canada de Santa Anita region, Alegria formation type locality, 30 
Caiiada del Capitan region : Vaqueros formation in, 32 ; see also Capitan Canyon 



Canada del Rodeo region, Tranquillon volcanics in, 33 

Canada FA Jolloru region : faulting in, 57 ; see also Jolloru Canyon region 

Canada El Morida region, faulting in, 57 

Canada Honda : Anita shale in, 26 ; Canada Honda fault in, 56 ; Espada formation 
type locality, 22 ; faulting in, 56, 57 ; Honda formation type locality, 22 

Canada Honda fault, 56 

Canada Honda region, Tranquillon volcanics in, 34 

"Capay" molluscan stage, 49 

Capitan Beach, Tranquillon volcanics at, 34 

Capitan Canyon: Alegria formation in, 30; Sespe formation in, 30; see also Caiiada 
del Capitan 

Capitan Canyon region : faulting in. 57 ; Sesi>e formation in, 31 

Capitan oil field, 67-68; Erburu fault in, 57, 67 ; structural map of, 66 

Capitan-Point Conception area, petroleum from, 67 

Capitan region. Las Yeguas fault in, 58 

Careaga formation, 39, 43, 44, 45-46, 47, 48, 58, 59, 60, 65; asphalt in, 75 ; ground water 

from, 82 
Careaga station region, Careaga formation type locality, 45 
Cascadian revolution, 65 

Casmalia Hills : Espada formation in, 23 ; Lospe formation in, 33 ; Orcutt formation 

type section in, 50 
Casmalia oil field, Lospe formation in, 33 
Cebada Canyon : Careaga formation in, 46 ; faulting in, 59 
Cebada member, Careaga formation, 46 
Celite, 75, 77 

Cephalopoda, from Jalama formation, 24 
Chico formation, correlation with Jalama formation, 24 
"Chico" molluscan stage, 49 
"Cierbo" molluscan stage, 48 
Coast Range orogeny, 65 
Coast Ranges, diastrophism, 61 
Cojo Canyon region : Alegria- Vaqueros contact in, 31, 32 ; bentonite in, 80 ; Monterey 

shale section in, 36 
Cojo fault, 56 

"Coldwater" sandstone, 24, 67, 68 ; see also Sacate formation 
"Coldwater" zone, Capitan oil field, 68 
Collophane, in Monterey shale, 41 
Corral Canyon, Erburu fault in, 57, 58 
Corral Canyon region, Sespe formation in, 31 
Covarrubias zone, Capitan oil field, 67 
Cox & Chilson, 81 
Cozy Dell shale, 24, 26, 27-28, pi. IIA, pi. 12B, 38, 49, 62; repetition along Bulito 

fault, 56 
Crassatella collina reef, in Gaviota formation, 29 
Cretaceous, 38, 39, 49, 51, 53, 54, 55. 56, 60, 61; Anita shale, 26; Espada formation, 

22-23; Jalama formation, 23-24 
Cretaceous and Eocene beds, unconformity between, pi. 12A 

Cretaceous rocks : Matilija sandstone unconformable on, 27 ; Sisquoc formation uncon- 
formable on, 44 
Cross, R. K., 9 

Cuarta Canyon, view west along coast from, pi. 16A 

Cuarta Canyon region : Alegria-Sespe gradational contact in, 30 ; Monterey shale in, 36 
Cuyama River, Obispo tuff at mouth of, 34 


de Anza, Juan Bautista, 10 

de la Guerra, Francisca, 12 

de la Guerra, Jose Antonio, 11, 12, 13 

de la Guerra, Maria Antonia, 11 

de la Guerra, Pablo, 11 

Deformation : see Geologic history, 60-65 

Delmontian stage, 34, 36, 37, 42, 44, 48, 63, 64 

Dendraster reef, Careaga formation, 46 

Desmoceras colusaensis zone, 49 



Diatomite, 75-79; gioimd water from, 82 ; in Monterey shale, 37, 41, 42, 43 ; in Sisquoc 

formation, 37, 38, 39, 41, 43-44, 64 
Diatoms : from Foxen formation, 45 ; from Monterey shale, 36, 40, 42 ; from Sisquoc 

formation, 44 
Dibblee. Albert, 12 
Dibblee, T. W., 9, 12 
Dibblee, Thos. Bloodgood, 12, 13 
Dibblee, W. C. H.. 78, 80 
Dibblee gravel quarry. 80-81 
Dicalite Company, 78. 79 
Dicalite diatomite quarries, 78-79 
"Domengine" molluscan stage, 49 
Drainage, southwestern Santa Barbara County, 19 
Drake area, petroleum exploration in, 68 

Drum Canyon : gravel quarry at mouth of, 81 ; Sisquoc formation in, 43 
Dune sand : in Careaga formation, 46 ; Recent, 39 

Echinarachniiis gabbii zone, 48 
Echinoidea, from Careaga formation, 47 
El Bulito Canyon, pi. 10-B ; see also Bulito Canyon 
El Chorro ranch, gravel quarry on, 81 
El Jaro Canyon : Espada formation in, 22 ; gravel quarries in, 80, 81 ; limestone in, 

40. 79, SO ; Tranquillon volcanics in, 34 
Eocene, 38. 49, 54, 55, 56, 61 -62, 80 ; Anita shale, 24. 25, 26; Cozy Dell shale, 24, 27-28; 

Matilija sandstone, 24, 25, 26-27; Sacata formation, 24, 28-29; Sierra Blanca 

limestone, 25-26 
Eocene and Cretaceous beds, unconformity between, pi. 12JL 
Eocene formations, petroleum from, 67, 68 
Eocene-Oligocene series, 24-30 
Eocene zone, Capitan oil field, 67, 68 
Erburu fault, 57-58, 67 
Erburu zones, Capitan oil field, 67 

Erosion cycles, southwestern Santa Barbara County, 19-20 
Espada Canyon, diatomite in, 77 
Espada formation. 22-23, 25, 33, 37, 38, 39, 49, 54, 61, 69; faulted against Gaviota 

formation. 57 ; faulted against Rincon shale, 57 
"Etchegoin" molluscan stage, 48 


Faulting : see Structure 

Fernando formation, equivalent of Careaga formation, 45 

Ferrelo, exploration of Santa Barbara coast. 9 

Figueroa Canyon region, San Marcos anticline in, 60 

Fish remains, in Sisquoc diatomite, 64 

Fish scales, from Monterey shale, 42 

Flagstone, 80 

Foraminifera : from Anita shale, 26 ; from Cozy Dell shale, 28 ; from Foxen formation, 
45 ; from Gaviota formation. 29 : from ]\Ionterey shale. 34. 36. 40. 42 : from 
Rincon shale, 33, 34 ; from Sacate formation, 29 ; from Sierra Blanca limestone, 
25-26 ; from Sisquoc formation, 44 

Foraminiferal stages, 48-49 

Formations, in southwestern Santa Barbara County, age of, 48-49 

Fossils: Actinocyclina aster, 26; Amnurellina, 28; Atnaurellina aff. moragai. 27; 
Amaurellina inezatia, 26; Aucella. 22; "Aucella'' crassicoUis, 23; "AucelW^ 
piochii, 23; Baculites, 23, 24; Calva steinyi, 23, 24; "Cardium hreicerii," 29; 
Crassnfella colUna, 29; Cj/praea, 28; DenHraster axhieyi. 46, 47; DiscocycJina 
psila. 26 ; Drillia graciosana, 47 ; Ectinochilus canalifer supraplicatiis. 27 ; Ficop- 
sh hornii, 27; Ficopsis ret)iondii. 27; Ficus gesieri, 29; Ficus maniillatus. 27 
Galeodea, 25: Galeodea susanae, 27; Gari hornii, 27; GlycyiJieris veatchii, 24 
Gypsina, 26; Inoceramus, 24; Lucina cf. annulafa. 47; Macot)ia nasiita, 32 
Macoma cf. nafiuta, 47; "Macrocallixta'' conradiana. 26; Macrocallista hornii 
27; ifactra ashburnerii. 24; Nassa moraniann, 47: Xemocardium linteum. 27 
Xummulites, 26; Olequahia cf. hornii, 27; OliveUa bipUcata, 47; Operculina 
26; Ostrea eldridgei, 32; Ostrea idriaensi^, 25, 28; Ostrea tayloriana, 29, 31 


Fossils — (Continued) 

Pecten maguolia, pi. 13A ; "Pecten peckhami," 42; Pecten (Amusium) lonipo- 
censis. 34 ; Pecten (Chlamyx) sespeenuLi, .32 ; Pecten (Chhimya) yneziana, 29, 31 ; 
Pecten (Lyropccten) cenosensi.s, 47; Pecten (Lyroperten) cxireUanun, 34; Pecten 
(Lyroperten ) vuuinoUa, 32, 34 ; Pecten (Patinopectcn) liealeyi, 47 ; Pecten (Pec- 
ten J vanrlecki, 32 ; Pitar uvusaniis, 27 ; Pseudocurdiuni cf. densatutn, 47 ; Rapana 
raqiierosensis, ,32; Schedocardia cf. hreirerii, 27; (Seraphs enntica, 27; Sipho- 
generina cnlloiiii. .3(5 ; Siphonalia inerrianii. 21) ; Tivela inczmia, 29, .31 ; Trachycar- 
diiiin raiiiicroKcnsi.-i. 32; Triyonitt, 23. 24; Triyonia erniisi. 24; Trigonia giboni- 
ana, 24; Trochitu radian.s, 47; Tinrilclln (ippluKie, 27; TurritcUa inezana, 32, 
1)1. 1.3.1 ,■ TurrJteUa inezanu var. altdcorona, 32; Turritelhi gonostoma hemphilli, 
47; Turritella ocoyuna, 34; Turritelhi scrippsensi.s, 27; Turritella temhlorensis, 
34 ; Turritella urnsnna, 25, 27 ; Turritella varinta, 29, 31 ; Turritella variata var. 
Juliana. 2N ; Valrulineria californica, 36 ; Venericardia hornii, 29 ; Venericardia cf. 
hornii. 2S ; "Venerupsis" cf. haunihali, 47; Volutaderma cf. gahhi. 24; YoWia cf. 
cooperii, 47. 

Foxen Canyon, Sisquoc fauna from, 44 

Foxen Canyon region, Siscjtioc formation type locality, 4.3 

Foxen formation, 39, 43, 44-45, 46, 48, 64 " 

Franciscan debris : in Jalama conglomerate, 23 ; in Lospe conglomerate, .33 ; in Paso 
Robles formation, 47 ; in Sespe conglomerate and red beds, 62 ; in Vaqueros con- 
glomerate, 32, 62 

Franciscan formation, 21-22, 33, 3.J, 37, .38, 39, 40, 49, 51, 53, 58, 60-61, 62, 63, 69; 
Honda shale member, 22 ; manganese in, 81 ; Matilija sandstone unconformable 
on, 27 ; Monterey shale unconformable on, 60 ; Sisquoc formation unconformable 
on, 44 ; source of Poppin shale iron oxides, 26 ; springs issuing from, 82 

"Franciscan" molluscan stage, 49 

Fremont, John C, 11 


Galeodea susanue zone, 49 

Gas, natural : see Petroleum, 67-74 

Gastropoda: from Gaviota formation, 29; from Careaga formation, 47; from Jalama 

formation. 24 ; from IMatilija sandstone, 27 ; from Sacate formation, 28 ; from 

Vaqueros formation, 32 
Gato Canyon region, Monterey shale in, 36, 37 
Gaviota, view northeast from, pi. 117? 

Gaviota Beach region : asphalt in, 75 ; Monterey conglomerate in, 40 ; Sisquoc forma- 
tion in, 43, 64 
Gaviota Canyon region : x4_legria-Sespe gradational contact in. .30 ; bentonite in, 80 ; 

Eocene-Oligocene series in, 24 ; Gaviota formation in, 29 ; Monterey shale in, 37 ; 

^Monterey shale section in, 36 ; Sisquoc formation in, 37 ; Vaqueros formation 

in, .32 
Gaviota formation, 24, 25, 28. 29-30, 31, pi. 117?. 38, 49, €2, 68 ; faulted against Espada 

formation, 57 ; faulting in, 57 ; petroleum from, 67, 68 
Gaviota Gorge, 53 
'"Gaviota" molluscan stage, 49 
Gaviota Pass region, Santa Ynez fault in, 54, 55 

Gaviota region : Monterey-Sisquoc disconformity in, .35 ; terrace deposits in, 50 
Gaviotito fault, 56; Cretaceous-Tertiary section uplifted along, 53 
Geographic features, southwestern Santa Barbara County, 14-15 
Geologic history, southwestern Santa Barbara County, 60-65 
Geomorphology, .southwestern Santa Barbara County, 17-20 
Gibraltar Dam region, faulting in, 54 
Gijote Canyon, bentonite in, 80 
Government Point, petroleum exploration at, 68 
Government Point region, Cojo fault in, 56 
(Jraciosa member, Careaga formation, 46 
Gravel, road : see Road gravel 

Great Lakes Carl)on Corporation, Dicalite Division, 78, 79 
Ground water, 82-83 


Harris region, Foxen formation type locality, 45 
History, southwe.stern Santa Barbara Couutv, 9-13 
Holli-ster, J. S., 83 
Hollister, James J., 12 

1950] INDEX 89 

Hollister, W. W., 12 

Hollister ranch, ground water on. 83 

Honda formation, 22, 38, 49, 60-61 

Honda School, faulting near. 57 

Horsetown formation, type, correlated Avith Kspada formation, 23 

"Horsetown" molluscan stage, 49 

Hot springs : see Springs, 82 

Hughes. A. W., 9 


"Jacalitos" molluscan stage, 48 

Jalama (Canyon) anticline. 53. 56 

Jalama Canyon, pi. lOJ. ; Anita shale in. 26 ; Jalama formation in, 23, 24 ; Matilija 

sandstone in, 27 ; Monterey diatomite in. 37 ; Monterey shale in, pi. 157? ; Poppin 

shale in. 26 ; Rincon claystone in. 33 ; Sierra Blanca limestone in. 25, 26 ; Si.squoc 

formation in. 43 
Jalama Canyon region, faulting in, 55 
Jalama Creek, Vaqueros couglomei-ate near, pi. 13.4 
Jalama formation, 23-24, 25, 26, pi. 10.1, pi. lOB, pi. 12.1. pi. 12B, 38, 49, 56, 61 ; 

faulted against Rincon shale, .54 
Jalama syncline, pi. 10.1 
Johns-Man\ ille diatomite quarries, 77-78 

Johns-Mauville Products Corporation, diatomite producers. 75. 77, 78 
Jolloru Canyon region : Tranquillon volcanics in, 34 ; see also Caiiada El Jolloru 
Jonata Park region : asphalt in. 75 : diatomite in. 77 
.Juncal formation, correlation with .\nita shale. 24 
Jurassic. 38, 39. 49. 55, 56, 59-61; Espada formation. 22-23; Franciscan formation, 

21-22; Honda formation, 22 


Knoxville formation. 39 ; type, correlated with Espada formation, 23 ; type, correlated 

with Honda formation. 22 
"Knoxville" molluscan stage, 49 

La Purisima Concepcion, Mission, 10 
La Salle Canyon, diatomite quarry in. 79 
La Salle Canyon region, limestone in, 79 
Laramide orogeny, 61 

Las Cruces : Crassatella coUina reef near. 29 : hot spring near. 82 
Las Cruces region : Gaviota formation in, 29 ; gravel quarry in, 81 ; Matilija sandstone 

in. 27 ; sulfur spring in, 55 
Las Yeguas Canyon, faulting in, 58 
Las Yeguas fault. 58 
Lasuen, Padre, 10 

Limestone. 79-80 ; in Monterey group, 40, 63, 80, 81 ; in Paso Robles formation, 47 
Limestone quarries. 34. 79-80 

Little Pine fault. 60 ; Sisquoc formation exposed on. 44 
Llanitos Canyon, bentonite in, 80 
Lompoc anticline, 58. 59 
Lompoc diatomite quarries, 37, 43, 78, 79 
Lompoc lowland. 51. 53. 58 
Lompoc oil field. 68-69; asphalt deposit at. 75; Franciscan formation in. 21; Lospe 

formation in. 33 ; Monterey shale in. 42 ; structure, 58, -59 
Lompoc Plain : alluvium in. 50. 51 : ground water in. 82 
Lompoc region : Careaga formation in. 45 ; limestone in. 79. 80 
LomiX)c Valley: diatomite deposits south of. 75. 76-77; ground water in, 82; history, 

13; Monterey shale in. 37; petroleum exploration in, 67; physiography. 18-19; 

structure, 51. 58 
Lompoc Valley region. Orcutt formation in, 50, 65 
Lompocan orogeny, 63, 65 

Los Alamos limestone, in Paso Robles formation, 47 
Los Alamos region, Los Alamos syncline in, 59 
Los Alamos .syncline. 51, 53, 59, 65 ; Sisquoc formation in, 44, 64 
Los Alamos trough : Foxen formation in, 64 ; Monterey sediments in, 63 


Los Alamos Valley : alluvium in, 51 ; Carcajia formation in, 45 ; Foxen formation in, 
45 ; ground water in, 82 ; Monterey shale in, 37 ; Orcutt formation in, 65 ; Paso 
Robles formation in, 47, 60; structure, 59-60; traversed by Los Alamos syn- 
cline, 51 

Los Amoles Canyon, gravel quarry in, 81 

Los Amoles Canyon region : flagstone from. 80 ; see also Amoles Creek region 

Los Olivos region, Los Alamos syncline in, 59 

Los Sauces Creek, Sierra Blanca limestone in, 25 

Lospe formation, 33, 37, 39, 62 

Luisian stage, 36, 41, 42, 48, 63 


Manganese ore, 81 -82 

"Marker diatomite," in Sisquoc formation, 43 

"Martinez" molluscan stage, 49 

Matilija Canyon: Cozy Dell shale type locality, 24; faulting at, 54; Matilija sand- 
stone type locality, 24 

Matilija sandstone, 24, 25, 26-27, 28, pi. lOA, pi. IIA, pi. 12A, 38, 49, 62; ground water 
from, 83 ; repetition along Bulito fault, 56 ; springs issuing from, 82 

Mattel's Tavern, 13 

"Meganos" molluscan stage, 49 

Mineral resources, southwestern Santa Barbara County, 67-83 

Mineral waters, 83 

Miocene, pi. 10.4, 38, 39, 48, 55, 56, 57, 62-64, 75, 76, 80; Lospe formation, 33; Mon- 
terey shale, 34-42; Rincon shale, 33; Sespe formation, 31; Sisquoc formation, 
43-44; Tranquillon volcanics, 34; Vaqueros formation, 31-32 

Miocene formations, folding, 53 

Missions, southwestern Santa Barbara County, 10 

Modelo formation, correlation with Monterey shale, 34 

Mohnian stage, 35, 36, 41, 42, 48, 63 

Mollusca : from Alegria formation, 31 ; from Careaga formation, 46, 47 ; from Eocene 
at Wons Canyon, 25 ; from Gaviota foi'mation, 29 ; fi'om Matilija sandstone, 27 ; 
from Monterey shale, 42 ; from Sierra Blanca limestone, 26 ; from Sisquoc forma- 
tion, 44 ; from Tranquillon volcanics, 34 ; from Vaqueros formation, 32 

Molluscan stages, 48-49 

Molluscan zones, 48-49 

Monterey sediments, tar-soaked, pi. 17 

Monterey shale, 25, pi. ISB, 33, 34-42, pi. 14, pi. 15.4, pi. 15B, pi. 16.4, 43. 44, 45, 48, 
54, 55, 56, 58, 59, 60, 63, 65, 68, 69 ; asphalt in. 75 ; bentonite in, 40, 80 ; Careaga 
formation unconformable on, 46 ; collophane in, 41 ; diatomite in, .37, 41, 42, 43, 
75-79; faulted against Rincon shale, 58; faulted against Sisquoc formation, 56; 
flagstone from, 80 ; Franciscan formation unconformably overlain by, 60 ; gravel 
quarries in, 81 ; ground water from, 82-83 ; limestone in, 40, 63, 79, 80, 81 ; mineral 
water from, 83 ; organic content, 42 ; petroleum in, 42, 63, 67, 69 ; silica in, 40, 
41, 63 ; springs issuing from, 82 

Monterey shale debris:. in Careaga formation, 46; in Orcutt formation, 50; in Paso 
Robles formation, 47 ; in Sisquoc formation, 44, 64 

"Moreno" molluscan stage, 49 


Natland, M. L., 9 

Natural gas : see Petroleum, 67-74 

"Neroly" molluscan stage, 48 

Nevadan orogeny, 61 

Nojoqui-Alisal area : faulting in, 52, 57; Sespe formation in, 62 ; spring in, 82; uncon- 
formity at base of Sespe in, 32 

Nojoqui Canyon, pi. 12i? ; Espada formation in, 22, 23 ; Jalama formation in, 23 ; 
Rincon claystone in, 33 ; Sierra Blanca limestone in, 25, 80 

Nojoqui Canyon region : unconformity in, pi. 12A ; Vaqueros formation in, 32 


Obispo tuff, 33, 34, 40 

Oil : see Petroleum, 67-74 

Oligocene, 38, 49, 55, 62; Alegria formation, 30-31; Gaviota formation, 24, 29-30; 

Sespe formation, 31 
Oligocene formations, petroleum from, 68 

1950] INDEX 91 

Orcutt formation, 39, 48, 50, 58, 65 

Orciitt oil field, Lospe formation in, 33 

Orcutt region, Orcutt formation type section in, 50 

Orefia, Caspar, 12 

Orogenies : see Geologic history, 60-65 

Oyster reefs, in Alegria formation, 30 


Pacifico, The, 55, 56 ; see also Santa Anita Canyon 

Pacifico anticline, 53, 55, 56 

Pacifico fault, 23. 54, 55-56; Cretaceous-Tertiary section uplifted along, 53 

Paleogeography : see Geologic history, 60-65 

Paleontology : see Fossils 

Panoche formation, correlation with Jalama formation, 24 

"Panoche" moUuscan stage, 49 

Paskenta formation, type, correlated with Espada formation, 23 

"Paskenta" raoUuscan stage, 4!) 

Paso Robles formation, 39, pi. 16B, 45, 46, 47, 48, 50, 51, 58, 60, 65; ground water 
from, 82 

Pecten coaJingaensis zone, 48 

Pelecypoda : from Careaga formation, 46, 47 ; from Gaviota formation. 29 ; from 
Jalama formation, 24 ; from Matilija sandstone, 27 ; from Monterey shale, 42 ; 
from Sacate formation, 28 ; from Yaqueros formation, 32 

Petroleum, 67-74; in Monterey shale, 42, 63; see also Capitan oil field, Casmalia oil 
field, Lompoc oil field, Santa Maria Valley oil field, Zaca oil field 

Petroleum, wells drilled for, 34, 60, 67, 70-74; Frank Buttram Xo. "Reuben" 1 well, 
59 ; General Petroleum Corporation Nos. "Erburu" 1 & 8 wells, 67 ; National 
Exploration Company well, 59 ; Richfield Oil Corporation No. "Skytt" 1 well, 
69 ; Rothschild Oil Company No. "Orella" 1 well, 68 ; Shell Oil Company No. 
"Covarrubias" 1-35 well, 67; Shell OU Company No. "Covarrubias" 1-36 weU, 
68 ; Shell Oil Company No. "Covarrubias" 1-37 well, 57 ; Shell Oil Company No. 
"Rutherford" 1 well, 68; Standard Oil Company No. "Gerber" 1 well, 68; 
Tidewater Associated Oil Company No. "Davis" 1 well, 69 ; Tidewater Asso- 
ciated Oil Company No. "Leonis" 1 well, 34 ; Union Oil Company No. "Purisima" 
19 well, 59 ; AVestern Gulf Oil Company No. "Hollister" 1 well, 68 ; Whittier 
Associates Nos. "Barham" 1, 2, & 3 wells, 69 ; Wilshire Oil Company No. 
"Hollister" 1 well, pi. 16A 

Phosphatic material : in Foxeu formation, 45 ; in Monterey shale, 41, 42 ; in Sisquoc 
formation, 44, 76 

Physiography, southwestern Santa Barbara County, 17-19 

"Pico" moUuscan stages, 48 

Pleistocene, 38, 39, 48, 51, 65; Orcutt formation, 50; Paso Robles formation, 47, 50; 
terrace deposits, 50 

Pleistocene orogeny, 58, 65 

Pliocene, 38, 39, 48, 64-65, 75; Careaga formation, 45-46; Foxen formation, 44-45; 
Paso Robles formation, 47, 50; Sisquoc formation, 43-44 

Poett, A. Dibblee. 80 

Point Arguello region, Honda shale in, 60 

Point Conception region: Alegria formation in, 30; petroleum in, 67, 68; Sisquoc 
formation in, 43 

Point Pederuales, Tranquillon volcanics at, 34 

Point Pcdernales region : Espada formation in, 22 ; faulting in. 56 ; Honda shale in, 22 

Point Sal formation, 33, 34 

Poppin shale, 26 

Portola, Caspar de, exploration in Santa Barbara region, 9-10 

Psilomelane, 81 

Purisima anticline, 58, 59, 69, 82 

Purisima anticline, western, 59 

Purisima Canyon : asphalt in, 75 ; Careaga formation in, 46 ; faulting in, 59 

Purisima Hills : alluvium in canyons of, 51 ; asphalt in, 75 ; Careaga formation in, 
45, 46, 64; diatomite in, 75. 77; Foxen formation in. 44. 45; Franciscan forma- 
tion in, 62 ; ground water in, 82 ; Monterey shale in, 37, 64 ; Paso Robles forma- 
tion in, 47 ; petroleum in, 67 ; petroleum exploration in, 67, 69; Sisquoc formation 
in, 43. 64 ; physiography, 18; springs in, 82 ; structure 51, 59, 65 

Pyrolusite, 81 





Quaternary system, 48, 51 

Quiota Canyon : offset by faulting, 55 ; Rincon claystone in, 33 ; Tranquillon vol- 

canics in, 34 || 

Quiota Canyon region : Santa Yiiez fault in, 54 ; Sespe formation in, 31 |i| 


Radiolaria, from Monterey shale, 42 ^ 

Rafaelan orogeny, 63-64 

Ramajal Canyon : Sierra Blanca limestone in, 2() ; A'acpieros formation in, pi. 13.4 

Rancho San Julian : see San Julian ranch 

Ranchos, southwestern Santa Rarhara County, 10-13 

Recent, 38, 39, 48 ; alluvium, 50-51 ; subsidence during, 51 

Recent stream gravels, quarry in, 81 

Redrock Mountain, asphalt in, 75 

Refugian fauna, from Las Cruces region, 28 

Refugian stage, 29, 31, 49, 62 

Refugio Canyon : anticline in Monterey shale, 68 ; Refugio fault in, 57 

Refugio Cove area, petroleum exploration in, 68 

Refugio fault, 57 

Refugio gas field, 68 

Refugio Pass, Matilija sandstone in, 27 

Relizian stage, 33, 34, 35, 36, 40, 42, 48, 63 

"Repetto" molluscan stage, 48 

Rhythmic bedding, in Monterey shale, 42 

Richfield Oil Corpoi-ation, 9 

Rincon shale, 31, .32, 33, 34, 35, 36, 38, 48. .54, 57, 62, 63, 68 ; faulted against Espada 

formation, 57 ; faulted against Jalama formation, 54 ; faulted against Monterey 

shale, 58 
Road gravel, 80-81 
Rothwell, W. T., 9 
Russel, C. E., 9 


Sacate Canyon : Sacate formation type locality, 28 ; Sisquoc formation in, 36 

Sacate formation, 24, 25, 27, 28-29, 30, pi. IIA, 38, 49, 62, 68; flagstone from, 80; 
petroleum from, 67, 68 

Salsipuedes Canyon : Anita shale in, 26 ; Espada formation in, 22, 23 ; Jalama forma- 
tion in, 23 

Salsipuedes Canyon region, diatomite in, 37, 77 

Salsipuedes Creek region : Sisquoc formation in, 43 ; structure, 78 

San Joaquin formation, correlated with Careaga, 47 

"San Joaquin" molluscan stage, 48 

San Julian Canyon, Rincon claystone in, 33 

San Julian ranch, 9, 11-13; Orassatella, collina reef near, 29; diatomite deposits on 
78 ; flagstone quarry on, 80 ; ground water on, 83 ; gravel quarry on, 80, 81 ; 
Sespe overlapped by Vaqueros on, 31 

San Julian Valley : Rincon claystone in, 33 ; Vaqueros formation in, 32 

San Julian Valley region, flagstone from, 80 

San Lucas Canyon: Espada formation in, 22, 23, 61; faulting at, 54, 55; Monterey 
shale in, 37 ; serpentine in, 22, 61 

San Lucas region, structure, 54 

San Luis Obispo County, Obispo tuff in, 33 

San Marcos anticline, 60 

San Marcos Pass region : Eocene in, 24 ; Gaviota formation in, 29 

San Miguel Canyon region, structure, 78 

San Miguelito Canyon region, diatomite in, 37, 77 

San Onofre Canyon, faulting of Gaviota sandstone in, 57 

San Pascual Canyon : Honda formation in, 22 ; Monterey shale in, 35 ; serpentine in, 22 

San Pascual Canyon region, limestone in, 79 

"San Pedro" molluscan stage, 48 

San Rafael foothills : alluvium in canyons of, 51 ; Careaga formation in, 45, 46 ; Foxen 
formation in, 45 ; ground water in, 82 ; Paso Robles formation in, 47, 60 ; petro- 
leum in, 67 ; physiography, 18; removal of Monterey shale in, 40 ; Sisquoc forma- 
tion in, 44, 46 ; Sisquoc-Monterey relationship in, 37, 63 ; springs in, 82 ; struc- 
ture, 60, 65 

1950] INDEX 93 

San Rafael Mountains : deformation. 61 : Espada formation in. 23 ; Franciscan forma- 
tion in. 21; manganese in. SI; pb.vsiographr, 17-18; Rafaelan orogeny in. 63; 
serpentine in, 22 ; Sierra Blanca limestone type locality, 25 ; source of Paso 
Robles formation. 65 ; spruigs in. S2 : structure. 60; uplifted bv faulting. 51 

San Rafael uplift. 51. 61, 62. 63, 64 

Santa Anita Canyon : Anita sbale type locality. 26 ; Jalama formation in. 23. 24 ; 
Poppin shale in. 26 ; Sespe formation in. 30 ; see also Cafiada de Santa Anita, 
The Pacific-o 

Santa Anita Creek, course along Pacifico fault. 55 

Santa Aque<la Canyon, geology in wells at, 60 

Santa Barbara. Mission. 10 

Santa Barbara County Road Department, SO, 81 

Santa Barbara embayment, 61. 62 

Santa Barbara-Goleta region. Sespe basal ojnglomerate in. 31 

Santa Barbara-Ventura Basin region, petroleum in. 67-68 

Santa lues. Mission. 10. 13. 82 

"Santa Margarita" shale. 43 

Santa Maria Basin: Careaga formation in, 45; deformation. 61; diatomite in. 75; 
Los Alamos sync-line in, 51 ; Lospe formation in. 33 : Monterey shale in. 35. 37; 
Paso Robles formation in. 47. 65: petroleum in. 67. 68-69; Point Sal formation 
in. 34 : structure. 59 ; submergence during Plioc-ene, 46, 65 

Santa Maria Basin, southern, stratigraphic column. 39 

Santa Maria Valley : Careaga formation in. 45 ; Foxen formation in, 45 

Santa Maria Valley oil field, effect of Rafaelan orogeny on. 63 

Santa Rita fault. 56-57 

Santa Rita Hills : Careaga formation in. 45. 46 : diatomite in. 76 ; faulting in. 56 ; 
petroleum exploration in, 67 ; Sisquoc formation in, 43 : Sisquoc-Monterey dis- 
conformity in. 35. 64 : structure, 53 

Santa Rita Hills region. TranquUIon volcanics in, 34. 63 

Santa Rita A" alley : Orcutt formation in. 50 ; part of Lompoc lowland structural 
province. 51. 58 ; Paso Robles formation in, 47, 50 ; structure, 58 

Santa Rosa anticline. 57 

Santa Rosa Hills : Jalama formation in. 24 : Matilija formation in. 27 : Monterey 
shale in. 35 : Rincon elaystone in, 33 ; Sac-ate formation in, 28 ; Sespe formation 
in. 31 ; structure. 53 

Santa Rosa HUls region, faulting in. 57 

Santa Rosa Park, gravel quarry near. 81 

Santa Rosa Ridge. Anita shale in. 26 

Santa Ynez fault. 54-55; hot springs along. 82; Santa Ynez Range uplifted along. 
51. 53, 54 

Santa Ynez fault, north branch. Cretaceous-Tertiary section uplifted along, 53 

Santa Ynez fault system. 54-56, 57 

Santa Ynez Mountain uplift. 51 

Santa Ynez Mountains, pi. lOB. IIA : alluvium in canyons of, 51 : Anita shale in. 26 ; 
bentonite in. SO ; Cozy Dell shale in. 27 : diatomite in. 75. 76-77; Espada forma- 
tion in. 22. 23 : flagstone rock in. 80 : Franciscan ( ? i formation in. 21 : Gaviota 
formation in. 29 ; Gaviota-Vaqueros contact in. 32 : geologic history. 61. 62. 63. 
64. 65 ; ground water in. 82 ; Honda shale in. 22 ; Jalama formation in. 23 : lime- 
stone in. 79 ; Matilija sandstone in. 26: Monterey shale in. 35-37, 42; Oligocene 
faulting. 62; petroleum exploration in. 67; physiography. 17; removal of Mon- 
terey shale in. 40 : Rincon daystoue in. 33 ; Sacate formation in. 28 ; seri)entine 
in. 22 ; Sespe formation in. 31 : Sierra Blanca limestone in. 25. 80 ; source of 
Paso Robles formation. 65; springs in. 82; structure, 53-58; Tranquillon vol- 
c-anics in. 34 ; Vaqueros formation in. 31. 32 

Santa Ynez Mountains, western, stratigraphic c-olumn, 38 

Santa Ynez-Pacifico fault zone. 53 

Santa Ynez Range, pi. lOA. 55 : Alegria formation in. 30 : Anita shale in. 26 : Cozy 
Dell shale in. 27 ; Cretac-eous and Eocene in. 61 ; Eocene-Oligocene series in, 
24-25 ; Gaviota formation type area. 29 : Jalama formation in. 23 ; Matilija 
sandstone in. 27 ; Monterey shale in. 35. 36. 37 : Sespe formation in. 31 ; Sisquoc 
formation in. 43 ; uplifted along Santa Ynez fault. 51. 54 ; Vaqueros formation 
in. 32 

Santa Ynez region : Careaga formation in. 45. 46 : diatomite in. 77 ; Fernando forma- 
tion in, 45 ; folding in, 59 






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